Three men who have been re-writing Ordnance Survey (OS) maps have received praise from the organisation for their thoroughness in re-surveying the heights of mountains.

In a feature for Wales Online on the work of Graham Jackson, John Barnard and Myrddyn Phillips, spokesman Paul Beachamp said: "We always hope OS is synonymous with accuracy so we are always delighted when people think they can make our maps more accurate."

He added most people cannot try to emulate them as an average GPS as used in a car is not designed for the kind of measuring the trio have been carrying out.

The feature noted how Welsh peaks Glyder Fawr and Tryfan have recently been checked and updates to Ordnance Survey maps made necessary, with the former shown to be 1,000.8 m (3,283 ft) high and the latter 917.5 m (3,010 ft) rather than 999 m and 915 m.

Last year a survey by the trio saw Sgurr nan Ceannaichean demoted from Munro status when it was found to be just short of 3,000 ft.

However, other OS measurements have been proved correct, such as August's check on Beinn a' Chleibh (916 m/3,006 ft), carried out for the Munro Society.

Posted by Dan Mirza