The charity side of the Flora London Marathon gives the event its unique character. A survey of runners last year showed that 76% ran for good causes, raising £24m between them to make it Britain's number one charity fundraiser.

The world's fastest runners are competing against each other, as are Britain's top club runners, international runners of various abilities, wheelchair racers, aspiring marathon runners and fun runners dedicated to fundraising.

Two competitors sure to always remember the day are Angela Stratford and Nigel Jones, from Cwmbran, south Wales, who will become the second couple to take their wedding vows while on the run during the London race.

Jenny Wood Allen, 89, of Dundee, is the oldest woman in the race - her 18th London Marathon since taking up running 18 years ago. The oldest man in the race is American Abraham Weintraub, who is 91.

And the youngest competitor will be James Bream, of Stafford, who celebrates his 18th birthday today. He only took up running in January, but is aiming to get round in under three-and-a-half hours.

The dedicated charity for this year race's is the Multiple Sclerosis Society, which will benefit from the event's high profile and also from having a guaranteed number of people running on its behalf.