As you can see it's a pretty bleak sort of day, but Margaret (who planned the outing) wanted me to see this wall. Her friend Henry Prout has just been given the Exmoor Society's top accolade in recognition of his work. He is a drystone-waller. 'The walls on Exmoor are different from others because the rocks are flat and slatey. When building up the two sides, the middle has to be filled with little stones, with big ones put in to keep the two sides together.' On a good day Henry can complete a length of three metres.