Sue Barker hosts live coverage of one of the nation's biggest sporting events, the Flora London Marathon. The world's top long distance runners will be doing battle over 26.2 miles in the race, which is now in its 29th year. Reigning champion Martin Lel is defending his title and looking for a record fourth win. But the Kenyan faces stiff opposition from a top class field, which includes the gold, silver and bronze winners at last year's Beijing Olympics. With Paula Radcliffe ruled out with a broken toe, Britain's best hope lies with Mara Yamauchi, but also lining up in the women's event are defending champion Irina Mikitenko of Germany, Olympic gold medallist Constantina Dita of Romania and Kenyan world champion Catherine Ndereba.