A record number of competitors have been taking part in the London Marathon.
Organisers said 40,382 people were on the gruelling 26.2-mile run, 1,242 more than last year's record high.
World records are being attempted by about 50 runners, including the fastest marathon in a sleeping bag and fastest marathon in Wellington boots.
The Duke and Duchess of Cambridge were joined by Prince Harry to start the elite men's and mass races.
The royal trio, who champion the race's official charity Head Together, also cheered runners along at different points of the route.
Armed police are watching over the 800,000 spectators, although the Met said there was no specific threat.
Steel road barriers have been placed at entrances to key roads along the route, to protect against any vehicle-based assault.
Among the runners was 47-year-old Gary McKee who completed his 100th marathon in 100 days.
Julie Henderson, a police officer who helped co-ordinate the response to the Westminster terror attack, took part to raise money for the Police Dependents' Charity while Mauro Pizzale, a City worker whose colleague's wife Aysha Frade was killed, ran to raise funds for Ms Frade's two children.
Sixteen MPs - five from Labour, nine Conservatives, one independent and one from the SNP - took part as are celebrities including pop band Scouting for Girls and radio host Chris Evans, who ran it for the third year in a row. Afterwards, he said it was harder than previous years as he is "heavier and it's hotter than in previous years".
David Weir broke a record when he won his seventh London marathon wheelchair race. He sped to victory in a time of one hour 31 minutes and six seconds. It is the first time he has won the race since 2012.
In the women's wheelchair race, Switzerland's Manuela Schar took the title for the first time.
Mary Keitany of Kenya won the women's race in a world record time of two hours, 17 minutes and one second, while another Kenyan, Daniel Wanjiru, won the men's race in two hours, five minutes and 56 seconds.