More than 1,300 cyclists are taking to central London's streets for today's Hero Ride, in aid of the armed forces charity Help for Heroes.
They include 300 fundraisers who arrived in the capital from Paris, having cycled from France over five days.
Those taking part are cycling more than 350 miles through the battlefields of the First and Second World Wars.
Other self-organised rides are taking place from various locations and meeting in Blackheath, southeast London, before culminating at Horse Guards Parade.
More top news
The desk and chair where Charles Dickens sat to write his final novels have been bought for the nation using a national heritage grant.
Lee Rigby's widow and son at moving ceremony to remember murdered soldier's "ultimate sacrifice".
Deputy Prime Minister Nick Clegg launched his election battlebus today with an attack on the Conservative Party.