The Royal Parks half marathon takes in four of London's best known parks - Hyde Park, Kensington Gardens, St James’s Park and The Green Park.
The route began in Hyde Park at 9am, heading through Green Park and on past Buckingham Palace into St James' Park. It then moves across Embankment taking in the Houses of Parliament and the London Eye.
Finally it loops back round through Admiralty Arch and Kensington Gardens before finishing back in Hyde Park.
When the sun comes out, Londoners head to the parks by the thousand.
But all that extra use has taken its toll on the Royal Parks deckchairs, and there's more hot weather on the way, so 6,720 of them will have their old canvas stripped and recycled into reusable bags. .
That means two miles (4,700 metres) of new canvas has had to be ordered. Enough to stretch from Buckingham Palace to Primrose Hill.