1. ITV Report

Britain's tallest mountain Ben Nevis 'grows' a metre since last survey

Ben Nevis Credit: PA

Britain's highest mountain is taller than previously thought and has "grown" by a metre in the last 65 years, experts have discovered.

Ben Nevis stands at 1,345m rather than the previously recorded height of 1,344m, a new Ordnance Survey (OS) calculation found.

The change, which will be displayed on all new OS maps, is not down to a geological movement but is simply due to improvements in technology that allow a more accurate reading than when the mountain was last surveyed in 1949.

A surveyor carrying equipment during the retriangulation of Britain between 1936 and 1962. Credit: PA

The new measurement was made by positioning a survey grade GPS receiver at the summit of Ben Nevis for two hours. Data was constantly fed to satellites and then checked by OS experts before being confirmed.

In 1949, it took a team of seven surveyors 20 nights to obtain their calculation, OS said.

A revised map of the area around Ben Nevis Credit: PA

The new height is exactly 1,344.527m but is rounded up to 1,345m officially.

Mark Greaves, OS geodetic consultant, was the first person to discover the change.

The new height relates to the highest natural point on the summit and was measured as 1,344.527m.

I double checked everything and asked others to do so too. What is amazing is how close the surveyors in 1949 were.

The measured height has changed by centimetres, but those centimetres mean we now need to round up rather than down. So that's why Ben Nevis will now be officially known as 1,345m.

– Mark Greaves
The mountain's summit Credit: PA

OS holds around 460 million geographic features in its database of the UK and regularly updates maps, with more than 10,000 changes possible each day.

OS marketing director Nick Giles said: "In reclassifying the height of Ben Nevis our map becomes even more precise.

"Now it's officially taller, I wonder how many will feel tempted to revisit its summit?"