A record breaking year for applications will see more than 40,000 people run the 39th London Marathon this morning.
Sir Andy Murray will be firing the starting gun at this year’s London Marathon from 09:05 BST.
The marathon has raised £1bn since the event started in 1981, according to race sponsors Virgin Money.
Despite the predicted wind and rain, runners are targeting over 80 Guinness World Records – including Sir Mo Farah, aiming to break his own British record.
Event director Hugh Brasher said: “No other mass participation event comes anywhere near this kind of fundraising.
“We would like to thank every runner, supporter, donator, charity, volunteer, sponsor, spectator, staff member and everyone else who has contributed to this wonderful total.”
Men’s world record holder Eliud Kipchoge and home favourite Sir Mo headline a strong field for the elite men’s race.
Kipchoge, the Olympic champion who holds the course record, is looking for a fourth win in the race in five years. He has not been beaten over 26.2 miles since the 2013 Berlin Marathon.
Eight-time winner David Weir is set to compete in the London Marathon wheelchair race for the 20th consecutive year.
A star-studded women’s field features four of the 10 fastest women of all time.
At the head of the pack last year’s winner Vivian Cheruiyot is set to renew her rivalry with fellow Kenyan and world record holder, Mary Keitany.
An eight-strong team from TV soap EastEnders running for Dementia Revolution on behalf of Dame Barbara Windsor, who was diagnosed with the disease in 2014.
Speaking about the £1bn raised for good causes, Mayor of London Sadiq Khan said: “This is an astonishing achievement and my congratulations go to everyone involved in making the London Marathon such a world-renowned fundraising success – helping millions of people over the last 38 years.”
Runners are expected to face strong winds and heavy rains, according to the Met Office.
The race will be broadcast live on BBC One.