The score was one game all when Peter Nicol, the defending champion, quit. The Scot had had diarrhoea for two days and, after only 41 minutes action, was so dehydrated he appeared ready to pass out.
Power, a Canadian, said: "It's very disappointing to win this way and not at all gratifying. I thought the Scots would have tried to do something to my food, not his." he joked.
Nicol led by 17-14 and 12-9 but could not take advantage. He walked from the court after losing six points in a row and did not return.
Neil Harvey, Nicol's coach, said: "He was devastated. He was in tears because he feels he has let everyone down, but it hasn't been that way at all. It's a very sad end to the week."
Just before the end, Power was involved in two confrontations with the referee over let decisions, when he had begun to realise something was wrong with Nicol.
Power said: "I was getting nervous he was so tired, and I could see he was hitting a wall. But it is a shocking way to end the British Open,"
On Saturday, New Zealand's Leilani Joyce claimed the biggest title of her career when she upset Cassie Campion, England's world champion and top seed, in the women's final.
Joyce, world No 3, is the first New Zealander to win squash's longest- established title since Susan Devoy in 1992. Her 5-9, 9-6, 9-3, 10-8 victory over Campion was revenge for semi-final defeats against her in the World and US Opens in October.