Varah was educated at Raine's Foundation Grammar School for Boys in Stepney and at Loughborough College. He was an excellent track and field athlete, and captain of the Loughborough College athletics team. He became a member of the Great Britain athletics team in 1965, and ran the second leg in a 4 x 800m relay that broke the world record at Crystal Palace in 1966. He competed for England in the 1966 British Empire and Commonwealth Games in Kingston, Jamaica and the 1967 Summer Universiade (the Tokyo World Student Games). At one point, he held the British Indoor Athletics record at 800 metres.