He was born in Cologne in 1924, where his father was serving in the British army of occupation. He went to Winchester College, where he excelled academically and learnt to fish on the college water on the Itchen, following in the steps of those giants of fishing literature Viscount Grey of Fallodon and G.E.M. Skues. Leaving school in 1942, he joined the King's Royal Rifle Corps, in which his distinguished father Maj-Gen T.N.F. Wilson had also served. Dermot Wilson was awarded the Military Cross in North West Europe for leading a patrol behind the enemy lines. He later said, "I didn't deserve it, I just got lost." He was also mentioned in dispatches.
After the war, he took the Foreign Office exam, finishing top. But when he found he was required to learn Mandarin Chinese, and would spend more than half of his career overseas, he decided against it. Instead, he joined the advertising agency J. Walter Thompson. There, in 1947, he met and married Renee Balsom, his support and mainstay for the next 49 years. He rose to become the youngest director of J. Walter Thompson, at that time, at the age of 37.
In 1968 he set up a mail- order tackle business, the first of its kind, at Nether Wallop, Hampshire, supplying a full range of fly-fishing tackle. It gave an extraordinarily good service. If you ordered flies from Dermot Wilson, they arrived in the post next day. The company grew to employ a staff of 14, many of them friends from his Greenjacket days. In 1981, ill-health caused him to give up, and the business was sold to the US company Orvis, who still run it successfully.
Dry fly fishing is a delicate art, and Wilson exemplified it. Once, on the Wiltshire Avon at Netton, I saw him kneel down and cast to a fish tucked in below the far bank. Using the finest and most delicate of tackle - a No 2 line and a tiny dry fly - he landed the fly to the inch, just above the fish, which immediately took it. A few inches wrong, and the current would have dragged the fly away. It was a perfect piece of fishing, elegantly executed.
Wilson was for some years Chairman of the Anglers Co-operative Association, which combats pollution of the rivers. He set up the Water Resources Board of the Salmon and Trout Association. He wrote for Country Life and the Field and was a popular lecturer at fishing gatherings.
Dermot Needham Furnival Wilson, fly fisherman: born Cologne 1 June 1924; married 1947 Renee Balsom (one son); died Salisbury 10 January 1996.