On your marks...

Where else would you find a convicted perjurer, a Michelin-star chef and a nearnaked student running side by side?

This eclectic mix is competing in this year's London Marathon, which is expected to attract about 33,000 runners and more than a million spectators.

While some will be aiming to break the world record of two hours four minutes and 55 seconds, others will be happy just to finish - and some may not make it at all.

The race, which is in its 23rd year, will be officially started by England rugby World Cup champions Jonny Wilkinson and Martin Johnson. There are three starting points in Greenwich: one for elite runners, another for club runners and a third

for amateurs. Spectators are encouraged to position themselves at specific vantage points as early as possible.

Favourite spots include Tower Bridge; Limehouse Causeway, off Westferry Road; Birdcage Walk; the London Eye; The Highway (best for disabled access); Docklands; and Jamaica Road, Bermondsey.

After crossing the finishing line, runners will be directed into Horse Guards Road to meet family and friends and collect their belongings. With huge crowds expected to converge on the capital at a time when the threat of terrorism is high, police are stepping up security and taking special precautions.

They have trained with organisers in special emergency drills on how to deal with anything from a gas leak to a bomb, during the race. Scotland Yard refused to reveal the total amount of officers on duty at the event but it is believed at least an extra 100 will be patrolling the route. Police emphasised there were no specific threats to the marathon.

Last year's women's champion and world record holder Paula Radcliffe is not competing this year, opting to concentrate on the Athens Olympics instead. Catherine Ndereba, who came second, is also not returning - opening up the women's category.

At William Hill, favourites to win are Ethiopian Gete Wami at 7-4 and Kenyan Joyce Chepchumba at 5-2. In the men's category, last year's champion Gezahegne Abera is joint favourite at 9-4. Despite being injured for much of last year, the Ethiopian is confident of victory and declares himself "as fit as a fiddle".

Kenyan Evans Rutto, who has run the distance in less than two hours six minutes but has never won a major race, is the other favourite.