Guy O. Nickalls came from a rowing family. His grandfather was one of the founders of the London Rowing Club and his father was a member of the 1908 gold medal eight from the Leander Club. The younger Nickalls was educated at Eton and Magdalen Colleges in Oxford, interrupted by his service with the Rifle Brigade in Thessaloníki, Greece. In 1920 he won the Silver Goblets & Nickalls’ Challenge Cup at Henley together with Richard Lucas, before winning the silver medal in the eights at the Antwerpen Olympics. In the following two years, rowing for Oxford, Nickalls lost in the Boat Race against Cambridge. In 1922, together with Lucas he managed to win the Silver Goblets & Nickalls’ Challenge Cup once again. Finally, in 1923 he won the Boat Race as a member of the Oxford crew and was appointed president of the Oxford University Boat Club. Nickalls was also the commentator for the first broadcast of the Boat Race by the BBC in 1927.
In 1928 Nickalls won the Stewards’ Fours as well as the Grand Challenge Cup at Henley with the Thames Rowing Club eights, qualifying to represent Great Britain at the 1928 Olympics, where he won his second silver medal. In the 1930s he also coached the Oxford crew in the Boat Race. After World War II, Nickalls became Chairman of the Amateur Rowing Association and merged his organization with the competing National Amateur Rowing Association, holding this position for 16 years. At Henley, he also acted as steward, organizing the regatta. In business, Nickalls joined the advertising firm of Alfred Pemberton Ltd in 1926, retiring in 1962 as vice-chairman. He was also an accomplished painter and wrote several books.