Cheats are on the run

London Marathon chiefs rarely name and shame the culprits - an equal mix of men and women, some of whom have raised suspicions by performing brilliantly in the over-60s age groups.

But the cheats are told of their disqualification in an official letter.

These days the evidence is usually conclusive given that the runners have an electronic chip fitted to their shoes which records their split times when they cross mats placed around the course. Photographs and videos are taken of key sections which cheats are known to dodge in their short cuts. But before the "Championchip" was introduced in 1996, the bandit catchers had to use eyewitness evidence and spot cheats through other methods.

Alan Storey, Britain's leading endurance coach who is a former chief bandit catcher, said the main job in the early days was to remove runners who had no official numbers.

Some runners would forge the bibs. When bar codes were introduced on the numbers, some even tried to beat the system by borrowing the codes off tins of baked beans or soup.

After that, it was a matter of catching people who clearly had not run the full distance.

He said: "An experienced eye can tell the difference between someone who has just joined in down the road and someone who has run the whole way."

Few runners admit to having cheated - even when the evidence is crystal clear. One woman, who recorded a superb time for her age despite weighing more than 16 stone, raised suspicion when she crossed the finish line on a warm day, wearing tights and a long-sleeve top.

Storey said: "You can tell if they have no perspiration and the hair is still lacquered. The favourite trick was to go into one of our toilets positioned every mile or so down the course wearing normal clothes and come out stripped to run and join the race as it is going past the toilet door.

"I hate people cheating. You get people in the middle of the field who have run faster than the winner for the second half of the race - and they may be significantly older and overweight. When you point out to them how fast they have run, the usual comment is they felt really good in the second half and there weren't any runners in the way. It's just laughable."

Storey believes the pressure of running for so much money for charity has also played a role in the hundreds of people who have been caught over the years.

He said: "If you take an entry from a charity, but can't complete the training, it is a difficult decision to pull out of the race because you don't get any kudos from that. So the question is whether you decide to cut a bit off and think nobody knows about it."