A mountain mapping specialist has questioned the border of England and Wales, saying that England may be owed some land.

Mountain surveyor Myrddyn Phillips, 58, says that the position of the border isn't there it's said to be on Ordnance Survey maps, reports WalesOnline.

He's been surveying Twyn Llech, the main eastern ridge of the Black Mountains, which is situated north of Abergavenny and south of Hay-on-Wire.

Mr Phillips, who's surveyed more than 600 hills and mountains in the last five years, believes there are discrepancies between what has been recorded on maps for more than 100 years, and what he found at Twyn Llech.

He believes after remeasuring the peak of the mountain, it's further into Wales than first thought, meaning the border is in the wrong place.

But the Ordnance Survey says the boundary is accurately shown on its mapping, saying: "Mr Phillips has taken measurements using the wrong scale mapping and technology which isn’t as advanced as what OS Surveyors use".


Mr Phillips, who established that Wales had an extra mountain in December, said: "There's evidence that shows the border follows the watershed [the ridge of land].


"The other evidence I would put forward is that it's an open mountain - by that I mean it doesn't have fences or walls on the top section - and the natural course for any boundary for such a mountain is to follow the watershed. So there is evidence there to say that's where the border is.


"The second time I was joined by a colleague, Mark Trengove, and I supplied the Ordnance Survey with the 10-figure grid reference of the summit. They informed me that the border on their digitised master map, which is the definitive placement of the border, was placed 12 metres to the east of the grid co-ordinates."

But just how far does this potential mistake go on for?

Mr Phillips, who runs a blog about his hill walking and mountain mapping, said: "We examined 350 metres in length and that anomaly applied to all of that land.



This discovery raises plenty of questions, including what it means for Wales?

Myrddyn isn't convinced it'll mean anything, soon. He said: "Nothing's going to alter in a rush, I know that much. There isn't even a mechanism in place to review the border between Wales and England."

What does Ordnance Survey say?




They add the following points:

  • Ordnance Survey works with the Boundary Commission to produce the Boundary-Line dataset (Open data product - https://www.ordnancesurvey.co.uk/business-and-government/products/boundaryline.html). This dataset is used across a number of OS products to show boundary information.
  • Boundary information is shown on Ordnance Survey paper and digital products, including 1:25 000 and 1:50 000 scale. It is important to recognise that this is a representation and not a scale of one to one. For info the drawn boundary line on 1:50 000 data is equivalent to 15 metres (50 ft) on the ground.
  • This scale (1:25k and 1:50k) of mapping should not be used to accurately measure boundary information on the ground. It is an indication on a 2D map.
  • We have checked the boundary information on our large scale product (OS MasterMap) and can confirm that the boundary is accurate.
  • We are not aware of any concerns from either Powys or Monmouthshire County Councils who both use boundary line information.

You can read Myrddyn's full detailed blog post, here .