HATCH End's Lara Nyman stormed to victory in the seventh annual Great River Swim in Chiswick - fighting off competition from 58 starters.
The record number of swimmers turned up for the 1,000 metre dash earlier this month only to watch as triathlete Lara claimed the win in record pace.
Her time of 12.36 was more than a minute quicker than the previous women's record, set three years ago, and just outside the men's record in the event.
It was the third time in seven years that a woman had won the race, and in this year's race the first man over the line was Marc Anley in 13.03. Winner of the Great River Swim Lara Nyman.