Sue Barker introduces coverage of the 28th running of the world's most famous road race - the Flora London Marathon. This year marks the centenary of the first-ever marathon at the 1908 Olympics when the race was first staged over the classic 26 mile, 385 yard distance from Windsor Castle to White City, London. 35,000 runners will start the journey that begins in Greenwich Park, passing world-famous landmarks such as Big Ben, Tower Bridge, the Houses of Parliament and Buckingham Palace. Steve Cram, Brendan Foster, Paul Dickenson and Tanni Grey-Thompson provide the commentary for the elite and wheelchair races as well as stories of determination, courage and even eccentricity among the amateur runners.