Earlier this week, a report written by the Oxford Economics Consultancy on behalf of Lloyds Banking Group was published which sought to measure the longer-term economic impact of the London Olympics and to assess the Games’ future legacy effects.

Not surprisingly, the consultancy found two industries in particular, tourism and construction, would benefit most, while the Games’ estimated economic impact was likely to be around £16.5billion over a 12-year period.

Bearing in mind the Games’ cost (officially £9.35bn of current expenditure, but likely to be considerably higher), some would argue this is hardly a fantastic return on investment over such a protracted period.

Oxford Economics also sought to establish a value for the Games’ feelgood factor’, starting from the premise that people generally acquire happiness by attending sporting and cultural events.

Volunteering adds to an individual’s sense of satisfaction, while a surge in national pride usually complements our happiness.

It’s undoubtedly true, too, that national events capable of uniting the nation, motivating children, promoting the value of sport and an awareness of disability supplements our sense of contentment.

Yet Oxford Economics also found that even if a feelgood factor resulted in a concurrent boost in consumer confidence, it is generally short-lived.

Economic legacies of sporting events are difficult to quantify, partly because they include intangibles such as the value to an Olympic host city of global television exposure, or measuring an increased participation in sports, or that rather airy ‘feelgood factor’ which supposedly inspires consumer confidence.

Superficially, however, the figures suggest the economy should receive a boost from the forthcoming Olympics.

It is anticipated 5.5 million day visitors will attend the London Games, including 294,000 international visitors.

Ticket sales should, according to the Office of Budget Responsibility, result in a much-needed 0.1 per cent increase in UK economic growth.

Assuming these figures are accurate, it’s comparatively easy to calculate likely expenditure and the subsequent economic ‘multiplier’ effect. Yet a raft of other calculations and forecasts look fanciful at best.

For example, the assertion by London’s Olympic Delivery Authority that 75p of every £1 spent on the Games will be ‘visible’ in 200 years’ time is perhaps the most outrageous claim made in sporting history.

Another survey, undertaken by Visa, suggests the foreign visitors pouring into London will spend a staggering £709m. Britons’ spending is forecast to rise by just £41m as this, say Visa, will either be incremental or money ordinarily spent on other forms of entertainment.

Were either forecast to prove accurate, it would be the first time in history domestic spending had risen in a country hosting a Games.

Nevertheless, such assertions have not prevented high street retailers in particular from suggesting the Olympics represents a major opportunity.

Countering this optimism, Neil Saunders, managing director of retail consultancy Conlumino, believes the economic impact will be much less than that resulting from the Queen’s diamond jubilee celebrations last month, primarily because no public holidays fall during the Games.

“The Jubilee was very much about the fact people had an extra day off,” he says, “That has a very tangible effect on food sales… but the Olympics isn’t like that.”

Following the wettest April and June on record and forecasts of more unsettled weather to come, the portents are not encouraging.

Furthermore, a large body of economists believe the Games will provide only a temporary boost.

Nick Moon, a director of GfK NOP Social Research, offers a particularly gloomy prognosis, maintaining: “The stagnant level of consumer confidence suggests the public is stuck in a period of constant depression.”

Thankfully, amid a raft of esoteric calculations and amorphous forecasts there is one economic report into the ‘Olympic effect’ which bases its conclusions on hard, measurable facts.

Earlier this year, Citigroup analysed data from ten Olympics held between 1964 and 2008. It found economic growth tended to be evident during the run-up to the event, although this usually plateaus prior to the Games’and weakens once the Olympic circus has left.

In London’s case, this is also likely to prove accurate. Before the curtain goes up on any Olympic Games, they’re little more than enormously expensive, state-backed construction projects.

During the Games themselves, a host nation’s economy is less productive as indigenous workers become more interested in seeking that elusive sporting feelgood factor delivered in the form of gold medals. Moreover, the forecast influx of foreign visitors awash with cash to spend rarely materialises.

Prior to the Beijing Games, economists estimated tourists would pump in around £500m to the Chinese economy; the actual figure was £93m.

As for a longer-term legacy, consider that prior to the Sydney Olympics, Australia witnessed a 16 per cent increase in short-term visitor numbers, but numbers steadily declined for three consecutive years after the Games had ended.

The Prime Minister believes London’s Olympics will lift the nation’s mood, although evidence suggests retailers hoping for a surge in consumer spending are likely to be disappointed.

If anything, some economists maintain demand will be depressed during the Games as many folks watch them on TV.

As for the most immeasurable intangible of all, the one underscored by a belief that the Olympics will result in a generation inspired by sport going on to lead a more active lifestyle, so saving the NHS billions in years to come, it’s understandable why some economists continue to question the sense in spending £9.35bn on a one-off event.

If promoting sport and inspiring people to lead an active lifestyle was the original, laudable aim, rather than encouraging economic growth via consumer spending, we may find it would have been better to spend £250m a year on sport (at current values) for the next 37 years.

After all, that would have cost the same amount of money as London’s Olympics.