The logistics of filming this colourful event are awesome: more than 30 fixed cameras, four mobile cameras, three helicopters and a motorbike cover every angle as more than
35,000 people run the 26 miles from Greenwich Park to the Mall.
Last year's winners
Eamonn Martin and Katrin Dorre are taking part again but the Chinese competitors WangJunxia and Qu Yunxia are threateningto give Ddrre a run for her money.
Of course, many people are running to raise money for charity, including celebrities such as Casualty's Cathy Shipton as well as hundreds of ordinary people who hope to finish despite their fancy dress. Commentary by David Coleman , Brendan Foster ,
Paul Dickenson and Richard Nerurkar.
Producers Martin Hopkins and Martin Webster
Editor Dave Gordon (Coverage continues at 12.35pm)