John Barnard surveying on one of the trio's previous ventures

Britain’s trio of amateur hill sleuths will feature in a BBC programme tomorrow as they help in the quest to find a county’s highest hill.

John Barnard, Myrddyn Phillips and Graham Jackson will join walkers’ pin-up Julia Bradbury and the Countryfile team as Tan Hill and Milk Hill battle it out for the status of Wiltshire’s highest point. Current Ordnance Survey maps show the former having a trig point one metre lower than a spot height on its neighbour on the North Wessex Downs.

Julia Bradbury will join the surveyors in their quest to settle the question of Wiltshire's highest hill

The trio, who have conducted numerous surveys of British hills, did a survey in April to find the highest point on each of the hills. An Ordnance Survey team then used these to conduct its own survey of the two. Mr Barnard said: “We had also taken GPS survey measurements ourselves and the results are in excellent agreement with those of the OS.”

The men have previously been responsible for the elevation of Mynydd Graig Goch to mountain status with confirmation that it topped 2,000ft (610m),  the OS’s recognised height for a mountain.

Tan Hill has a triangulation pillar marked on maps as being 294m (965ft), whereas Milk Hill, 2km (1¼ miles) to the East, has a spot height marked as 295m (968ft).

The Julia Bradbury-fronted programme will reveal the winner of the survey tomorrow, Sunday, at 7pm.