Policy Papers

Brexit and the history of policing the Irish border

Evan Smith |

Executive Summary

  • Since 1949, citizens from the Republic of Ireland have had the right to freely enter, reside and work in the UK.
  • Even at the height of the conflict, there was still significant cross-border movement between Northern Ireland and the Republic of Ireland.
  • Between the outbreak of the conflict in 1969 and the Anglo-Irish Agreement in 1985, the British authorities found it difficult to police the Irish border.
  • Checkpoints were costly to run, and the border remained vulnerable to attack by the Irish Republican Army.
  • Any establishment of a strict border system, if demanded by the European Union, between the two Irelands would be greatly detrimental to the 1998 peace agreement and wider Anglo-Irish relations.

With the outcome of the recent ‘Brexit’ referendum being a majority vote for Britain to leave the European Union, the question of what happens to the border between Northern Ireland and the Republic of Ireland has been raised. The majority of people in Northern Ireland voted to ‘remain’, except for a strong Loyalist vote for ‘leave’, in certain parts of Belfast.  The Democratic Unionist Party officially backed a vote to ‘leave’. Despite traditionally being a Eurosceptic party, Sinn Fein has seen this as an opportunity to call for the re-unification of Ireland and declared during the referendum campaign that a vote to ‘remain’ was in the interests of closer ties between the two Irelands.

The victory of the ‘leave’ campaign raises the possibility of an established border control system on the Irish border, with the task of heavily monitoring movement between an EU and a non-EU country. Other EU/non-EU borders, such as the border between Greece and Turkey, have become flashpoints on the periphery of ‘Fortress Europe’, particularly concerning the movement of potential ‘terrorists’ amongst those fleeing the war in Syria and Iraq, and some commentators have raised concerns about the Irish border becoming a similar flashpoint.

During the conflict in Northern Ireland, the British, Northern Irish and Irish authorities were also concerned about this border, the movement of potential terrorists, and how travel across it would be monitored. The British were most concerned about potential terrorists crossing the border from the Republic into Northern Ireland and Northern Irish terror suspects fleeing to the South. As Henry Patterson has written, ‘the border was of major strategic importance to the IRA campaign’ and it preoccupied both the British and Irish governments. Throughout the 1970s, the British, as well as the Northern Irish government in Stormont and the Royal Ulster Constabulary (RUC), attempted a series of different tactics to prevent border crossings, starting with an explicitly militarised approach and moving to the experimentation with a more traditional immigration control system. It was not until the Anglo-Irish Agreements in the mid-1980s that the Irish border was effectively controlled from both the British and Irish sides.

Irish migration to Britain before the conflict

The Irish border was originally a contested boundary and its existence remains disputed in international law, as well as within the Irish Constitution. Since partition in the 1920s, the border between Northern Ireland and the Irish Free State had been porous, with relatively free movement on both sides of the border. After the creation of the Republic of Ireland in 1949, Irish citizens were placed in a special category by the UK authorities as ‘neither aliens nor subjects’ and were granted the right to enter, reside and work in the UK unrestricted. Kathleen Paul has estimated that this provision allowed an average of 50-60,000 Irish migrants per year to enter Britain between the late 1940s and the early 1960s.

Before the outbreak of the conflict in August 1969, the only republican activity seen across the border area in the post-war era was the short-lived ‘border campaigns’ of the Irish Republican Army (IRA) in the late 1950s and early 1960s. These border campaigns consisted of attacks on RUC barracks inside Northern Ireland and bombings of other government installations within the border area. In retaliation, hundreds of suspected IRA members were detained and gaoled in both Northern Ireland and the Republic of Ireland. These campaigns were, in general, viewed as tactically disastrous for the small organisation and in February 1962, the border campaign was called off. Until the arrival of British troops in 1969, the IRA’s militarism lay dormant and the border remained relatively peaceful.

The beginning of the conflict

After a series of battles between Royal Ulster Constabulary members and Catholic civil rights protestors in Belfast and Derry, the British government was asked by the Protestant leadership in Stormont to send troops to pacify the situation in August 1969. Although the original intention was to ‘protect’ the Catholic community in Northern Ireland from sectarian violence, the presence of the British Army soon resembled an occupying force and the IRA remobilised to drive the British out of the region.

Soon after this phase of ‘the Troubles’ began, the border area became a focal point of the conflict – for the movement of republican fighters between the North and the South, and for attacks by Republicans upon the British Army and RUC patrols situated at the border. A report by the British Army (Control of Northern Ireland Borders: Preliminary Report, 17 May, 1971, CJ 4/424) outlined the problem as such:

The security problem in Northern Ireland is influenced by the relative ease with which men with subversive intent, with or without arms, ammunition or explosives, can enter Northern Ireland; and wanted men can escape. The movement occurs over the land border with Eire; though normal sea and air points of entry into Northern Ireland; and by illegal movement by sea and air.

In August 1970, a car bomb killed two RUC members at Crossmaglen, which resulted in a partial closure of the border, blocking ‘unapproved roads in South Armagh, Castlederg Salient and Londonderry [sic] Salient’. According to the 1971 report on the border closure, 51 roads were closed, using spikes, but over the next two months, there were 83 recorded incidents of the blocks being removed from 29 different roads. The report found that:

Resistance to the blocks was so determined and the result so ineffective that it was decided to abandon the operation. Spikes and other blocks were gradually removed during the period Oct – Dec 1970, and the sites tidied up.

As the violence in Northern Ireland increased over the next few years, various sections of the British and Northern Irish authorities attempted to devise ways of preventing Republican fighters from crossing the border, or from attacking border patrols inside Northern Ireland.  The British Army attempted to transform the border into a militarised checkpoint, relying on a combination of blocking off ‘unapproved’ roads and vehicle/personnel checks at others. Central to this was an emphasis on vehicle and identification checks. However there were several problems that the Army and the RUC encountered when trying to enforce this policy.

Firstly, they found that there was too much border to guard at one time. A 1973 Home Office report (Border Control: Vehicle Documentation, 1 February, 1973, CJ 4/424) stated:

There are 303 miles of the border. There are 20 approved roads, 187 approved roads and 17 concession routes… The facilities for crossing the border are much greater than the number of cross-border roads. In particular there are 30 miles of water, numerous lanes and smugglers’ pads and border lands which are easily negotiable on foot.

The Northern Ireland Office found that if the entire border was to be guarded, the burden would fall to the RUC and proposed ‘strict control along a limited sector only’, based on where the border was most likely to be traversed by ‘subversive’ elements. Stormont’s Government Security Unit proposed in March 1972 that there were two solutions patrolling the entire border. The first option was a ‘sealing’ of the border, while the second was a partial prevention of entry, particularly along ‘unapproved’ roads.

‘Sealing’ the border was seen as the ‘nuclear’ option as it entailed converting the entire border into ‘a militarized frontier, with a continuous glacis, minefield or other impenetrable barrier under constant surveillance’. ‘The only points of entry’, the Unit then proposed, ‘would then be by the way of the 20 approved crossings, with 100% checks on all persons, vehicles and loads’. This was an extreme option and the Unit warned:

It may be necessary to bring home to members of Parliament and the public what the ‘sealing’ of the Border really implies. Any measures on the lines of those described would be enormously costly in time, money and manpower; they would involve a dislocation of all legitimate cross-Border activities; they would have to be supported by a defensive blockade of the entire coastline; and their political and economic implications would be entirely unacceptable within the context of [the] EEC.

More favourable was the partial prevention of entry, which would mean the blocking of some more difficult to police roads and the interception of vehicles on the remaining roads. However this still presented problems, with the Unit stating that any road closures would need to be weighed against ‘the hardship likely to be caused, the resistance to be encountered and the tying down of manpower to ensure that closures remain effective.’ The Unit warned that partial closures still required a large amount of manpower to guard both the closed and open routes. Furthermore, it was warned that ‘[p]ermanent check-points at vehicle crossings [would] also present shop window targets’ for attacks by Republican fighters.

With the focus on intercepting vehicles crossing the border and the use of checkpoints, there was also disagreement over how these interceptions would function. At first, there was a push for compulsory ID checks on all of those who crossed the border, but it was acknowledged that this was ‘a valuable aid to the identification of drivers, but that this did not help in relation to passengers’, as non-drivers in both the UK and the Republic of Ireland were not required to hold identification papers at all times.

A proposed alternative to the checking of driver’s licences was the checking of vehicle registration papers. However it was deemed that this raised too many obstacles, particularly as numerous vehicles crossing the border (delivery trucks, hire cars, etc) would not necessarily have these registration papers in the vehicle. Furthermore, a report by the Ministry of Home Affairs mentioned that there was ‘a well-founded objection to keeping registration books in cars because both can be stolen together.’

To get around these specific problems, the Central Secretariat at Stormont floated whether all people living or working within a designated border zone could be issued with a special vehicle permit. In the same document, it was suggested ‘if there is a case on security grounds for imposing this requirement, it should be applied over the whole province and not only in a specified border area.’ However with both suggestions, those in Stormont felt that this would be an onerous requirement and that permits could not quickly issued. The conclusion to these proposed checks was that ‘[t]he imposition of a requirement to carry vehicle documents would not necessarily bring about any substantial improvement in border security’ and that ‘[e]nforcement would present considerable difficulties’.

Alongside the push for a greater insistence on documentation for those crossing the border, the Army also pushed for greater powers of search and seizure of suspected vehicles. As a 1973 Home Office document stated, ‘’[t]he army would like a clear power to seize vehicles so that they could be removed for close scrutiny’, and called for an expansion of the Special Powers Act 1922 to cover this demand. While the requirements for compulsory carriage of documents were not followed through, greater powers of search and seizure were incorporated into the Northern Ireland (Emergency Provisions) Act 1973.

After much deliberation about the border check system already implemented, it was still debated whether the intense scrutiny placed upon cross-border travelling had brought many tangible benefits, particularly considering the amount of manpower involved. For example, the previously mentioned British Army report from May 1971 stated:

In the first four months of 1971, over 200,000 cars have been searched in Northern Ireland and in only about 10 have wanted men, arms or explosives been found; some 25 or more evaded road checks.

However the report also qualified that there were some gains to this approach, adding:

Nevertheless the security dividend from a tighter control of the border area must not be underestimated: a reduction in cross-border explosive attacks and the interception of wanted or wounded men escaping from Belfast are typical potential gains. (My emphasis)

After 1972 (the deadliest year in the 30-year conflict), the Provisional IRA shifted tactics to attacking targets on the British mainland, while Loyalists targeted civilians in the Republic of Ireland. Although there were two bombings at the Old Bailey in 1972, it was not until the following year that the British mainland campaign began in earnest, with retaliation by Loyalists through the bombing of civilian areas in the South. At the same time, the British authorities believed there was an increase in the number of incidents in Northern Ireland perpetrated by Republicans crossing the border from the Republic. The British Army estimated that ‘terrorists based in the Republic have been responsible for at least 497 incidents in 1973’. The spread of the conflict from Northern Ireland to Britain and the Republic of Ireland worried the British and Irish authorities, although there was little Anglo-Irish co-operation at this stage.

The use of exclusion orders and the Prevention of Terrorism Acts

The bombing of two Birmingham pubs in October 1974 led to the newly installed Wilson government to rush through the Prevention of Terrorism Act (Temporary Provisions) Act 1974. As well as extended powers of detention for those suspected of terrorism offences in Britain, the Act also gave powers to regulate the travel of people from Northern Ireland to England, Wales and Scotland (Great Britain) and exclude/deport those suspected of acts ‘designed to influence public opinion or Government policy with respect to affairs in Northern Ireland.’ Other forms of international terrorism, such as that extending from the Middle East or North Africa, was not covered by the Act.

In 1976, the Act was amended to cover people travelling from the British mainland to Northern Ireland, but crucially neither act dealt with suspects travelling between Northern Ireland and the Republic of Ireland. The 1976 Act also, for the first time, introduced (under Section 13) checkpoints at ports of entry between Great Britain and Northern Ireland, even though both regions belonged to the United Kingdom and travel between them by UK citizens was completely allowed. Because the monitoring of travellers between Northern Ireland and Great Britain was implemented under the Prevention of Terrorism Act and not the Immigration Act 1971, immigration officers did not work at these port entry points.  Control points were staffed by the police (often Special Branch officers). The police, in some cases, used landing and embarkation cards similar to those used under the Immigration Act for all non-UK passport holders.  For many who travelled between Great Britain and Northern Ireland, the line blurred between border control official and police officer. In his 1978-79 review of the Prevention of Terrorism Act, Lord Shackleton wrote, ‘a passenger may thus be in doubt whether he is speaking to a police officer, an immigration officer or some other official’ and that ‘[h]is attempts to find out may not always meet with success’. Besides the increased monitoring of the movement between Great Britain and Northern Ireland, the British authorities still relied on policing the Irish border though a series of checkpoints.

A continuation of the checkpoint system

In the same year that the Prevention of Terrorism Act was introduced, the Northern Ireland Office warned that policing the border in this manner still involved massive amounts of staffing, with a report stating:

Since 1971 nearly 20% of regular Army manpower in the Province has been devoted to maintaining the integrity of the Border areas and the Border itself. Experience has shown that because of the length and nature of the Border, the Army, no matter how many men they deploy cannot ensure total security.

Furthermore, the report argued that border area was not topographically ideal for surveillance.  Certain technologies, such as radar and unattended ground sensors, had limited success in helping the authorities detect subversives crossing the border.

To overcome this, the report revisited the idea of laying mines, erecting wires or some other kind of immovable physical obstacle across the border to restrict illegal crossings. However it was felt that the use of either mines or wires had ‘an unpleasant “East German” connotation and would be indicative of a siege mentality’: ‘[m]ines would be dangerous and wire would be unsightly’ concluded the report. (Northern Ireland Office, Picquets and Unmanned Devices on the Border, 2 December 1976, CJ 4/1758).

The Shackleton Inquiry and the Anglo-Irish Agreement

In 1978, Lord Shackleton undertook a review of the Prevention of Terrorism Act 1976, which included reviewing the border control aspects of the legislation. The 1976 Act had broadened the scope for the dispensing of exclusion orders and Shackleton’s main suggestion concerning exclusion orders was that they be subject to periodic review, in case an excluded person’s circumstances had changed since the order was issued. Apart from this, there was little mention of the issue of cross-border terrorism and subversion. At the same time, the Home Office briefly considered whether the transformation of the checkpoint system into a more formal border control system across the Irish border would help in the fight against Republican (and Loyalist) violence. However it was soon concluded that, like the checkpoint system, control of the border between Northern Ireland and the Republic would still require an excessive burden of staffing. The Home Office report, ‘Difficulties Over Proposal for Immigration Control Between the United Kingdom and the Republic of Ireland’, stated categorically, ‘A system of full immigration control would be costly, most difficult to administer, and of limited effectiveness’.

From the early 1970s onwards, there was much consternation amongst the British authorities that the Irish Gardaí did little to maintain the integrity of the border. The British even accused the Gardaí of having actively assisted Republicans moving across the border. The Anglo-Irish Agreement, negotiated by Margaret Thatcher and Garret FitzGerald in 1985, put an end to this (at least officially), with Article 9 of the Agreement stating:

With a view to enhancing cross-border co-operation on security matters, the Conference shall set in hand a programme of work to be undertaken by the Commissioner of the Garda Siochána and the Chief Constable of the Royal Ulster Constabulary and, where appropriate, groups of officials, in such areas as threat assessments, exchange of information, liaison structures, technical co-operation, training of personnel, and operational resources.

Cross-border co-operation was reinforced by the Good Friday Agreement, signed by the British and Irish governments in April 1998, which sought to redevelop the border areas as a symbol of working towards social cohesion between the two Irelands. Despite some difficulties, this cross-border co-operation has been largely successful and despite some passport checks on the Republic of Ireland side, movement across the border in the last two decades has been a relatively painless affair.

The edges of ‘Fortress Europe’

While allowing free movement within its borders, the European Union has strict borders with non-EU countries. In response to the large influx of refugees from the Middle East and North Africa to southern Europe in 2014-15, particularly at the border between Greece and Turkey, the EU established greater border security between EU and non-EU countries (this does not affect Switzerland and Norway, which remain EEA countries). In December 2015, a new European Border and Coast Guard was created ‘to ensure a shared and strong management of the external borders’. This new border control system will see a vast increase in manpower for ‘rapid intervention’ in border security issues and new powers granted to pre-emptively intervene in third party countries to prevent breaches of the border system, as well as ‘mandatory systemic checks of EU citizens’ at both land and sea borders.

Although it is unclear what form of border might prevail between Northern Ireland and the Republic of Ireland, most agree that the type of border that the European Union demands between EU and non-EU countries would fundamentally disrupt the cross-border relationships that already exist. Since the ‘Brexit’ vote, several TDs in the Irish Dáil Éireann have raised concern that this vote might negatively impact upon cross-border relations and that the peace agreement that has been in place since 1998 might be in jeopardy.


Although the conflict in Northern Ireland has, for the most part, ended, it would be wise to heed the 1978 warning about the difficulty of implementing an immigration control system between Northern Ireland and the Republic of Ireland. Since the creation of the Republic of Ireland in 1949, there have been no immigration restrictions between the UK and Ireland and the only controls have been applied have been the exclusion orders under the Prevention of Terrorism Acts (which were made redundant in 2000 by the Terrorism Act).

To establish a new border control system at the land border between Northern Ireland and the Republic would be a blow to the peace settlement forged in 1998, and to wider Anglo-Irish relations. However the alternatives to this are just as problematic for the British government. To allow free movement across the Irish border would entail either Britain remaining part of the European Economic Area (similar to Norway or Switzerland) or the reunification of Ireland. These alternatives present their own problems, with sections of British society being unhappy with either. The relationship that Britain had with the Republic of Ireland was an imperial anachronism that continued into the era of the EEC/EU, primarily because the Irish government didn’t want to be left behind by Britain (its biggest trading partner at the time). In a bid to reassert its sovereignty, Britain has thus potentially wrecked the only recently repaired relationship with its closest neighbour.

Further Reading

John Coakley & Liam O’Dowd, ‘The Transformation of the Irish Border’, Political Geography, 26/8 (2007) pp. 877-885.

Vicki Conway, ‘Policing the Border During the Troubles’, Human Rights in Ireland blog, October 16, 2012, http://humanrights.ie/civil-liberties/policing-the-border-during-the-troubles/.

Enda Delaney, The Irish in Post-War Britain (Oxford: Oxford University Press, 2013).

Henry Patterson, Ireland’s Violent Frontier: The Border and Anglo-Irish Relations During the Troubles (Houndmills: Palgrave Macmillan, 2013).

Kathleen Paul, Whitewashing Britain: Race and Citizenship in the Post-War Era (Ithaca: Cornell University Press, 1997).

Lord Shackleton, Review of the Operation of the Prevention of Terrorism (Temporary Provisions) Acts of 1974 and 1976 (London: HMSO 1978).


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