Athletes train for years to do their best at the Olympic Games. They aim to arrive in the best physical shape, with their tactics clear and their preparation perfect. But sometimes, fate will still trip them up.

Sweden's Gert Fredriksson, who competed at the top level over the course of more than two decades, is arguably the greatest canoeist of all time. He began competing in 1942, but the Second World War meant he didn't make his Olympic debut until 1948, by which time he was 28. He won two gold medals in London, then added a gold and a silver four years later in Helsinki and then two more golds in Melbourne in 1956.

It was in Helsinki that the butterfly first truly rose to prominence. It had only been adopted relatively recently by top-class swimmers, and was not yet sufficiently established to be given a race of its own, in instead being classed as being a type of breaststroke.