London Marathon organisers said Sunday's edition of the event set a world record for the number of finishers, eclipsing the previous mark of 55 646 set at last year's New York City Marathon.
Organisers did not provide a final figure but said a new mark had been set at 6:35 p.m. (1735 GMT) with runners still crossing the finish line.
Kenyan Sabastian Sawe won the men's elite race while Ethiopian Tigst Assefa shattered the women's-only world record.
"The TCS London Marathon is the world's greatest marathon, and it is now officially the world's biggest marathon," Hugh Brasher, CEO of London Marathon Events, said in a statement on Sunday.
A record 56 000 runners had been expected to participate in the 42.195 km race that started at Greenwich Park, snaked along the River Thames before finishing on The Mall.