HAVING devoted much of his 42 years to abusing his body, Irvine Welsh, the enfant terrible of British literature, yesterday looked remarkably fit as he completed the 21st London marathon.

A considerable number of the long-distance runners looked in far worse condition at the end of the gruelling course. He had decided to run to raise funds for multiple sclerosis after a friend was diagnosed with the disease.

Crossing the finishing line wearing an orange running vest and blue baseball cap, the clock showed it had taken him four hours and 50 minutes to cover the 26 miles and 384 yards. Not an unrespectable time for someone who has enjoyed life to such excess.

However, he reckoned he had been delayed at least five minutes at the start. ''Four and three quarters hours would be nearer the true time, and I am reasonably pleased with that.'' he said.

''In any case, I was not all that worried about how long I took,'' he said. ''I was more concerned about finishing. I couldn't be sure I would because the most I have done in training is 15 or 16 miles''

Indeed, Welsh and the 29,999 others who took part could feel justifiably proud of their achievements.

As, usual it was a carnival occasion for the fun runners. As tradition demands, many of them ran in costume. There was an abundance of Supermen and Elvises and an impressive group of rhinos.

Each competitor was rewarded with a goody-bag containing amongst other things a T-shirt, a biscuit, sandwiches, and a soft drink for their efforts. The roll-on deodorant and sticking plasters also in the bag were probably more practical gifts.

All proudly wore the gold 2001 marathon medal with its green, yellow, and red ribbon as they exited the Mall at the end of the marathon. Welsh was as pleased as anyone else who had completed the course.

''Tonight I intend to get pished,'' he declared. ''I think I deserve it.''

Wading through a sea of discarded silver and white capes handed out to competitors to maintain body temperatures, the author of Trainspotting had no doubt when asked which was the more difficult - writing or taking part in his first-ever marathon?

''Writing books is much easier,'' he said. ''You can sit down to do that.''

Since the New Year, when he began serious training, he had given up everything to ensure that he would complete the course.

Everything? ''Absolutely ... drink, drugs, tea, coffee, and going out. I have had no social life at all,'' he said.

''I am going to a party in Manchester next week,'' he said, as he took the advice of officials to carry on walking so his muscles would not seize up.

''I expect to have quite a hangover after that.''

Since January, Welsh has stuck rigidly to his training programme, running three days a week for at least an hour.

He said he was now probably the fittest he has been since he was 11 years of age, and he plans not to lose it all.

But would he do it all again? ''Seeing some of the literature today for the New York marathon makes it tempting.

''It would be really great running through Brooklyn and the Bronx, and if the crowds are as friendly as they were here today, who knows.

''But then again you have to give up too much and I don't think I want to do that again. A half-marathon sounds a more realistic prospect, so I am more likely to run in Glasgow,'' he said.

At the end of the race most of the competitors called home to report their success. Others went through it mile by mile with friends who had cheered them over the finish line.

Only The Herald was there to greet Irvine Welsh.

''I was going great guns for the first18 miles or so, right up until the Isle of Dogs where I did a lot of my training. In fact, as I went over Tower Bridge I thought I was in with a chance of putting in a really good time,'' he said.

Welsh was just one of a large group of Scots taking part. Jenny Wood Allen, 89, a great-grandmother from Dundee, was the oldest woman in the race. It was the 18th time she had taken part.

Having run in the Edinburgh marathon, Neil Slater from Bellshill, a ScotRail manager at the Yoker depot in Glasgow was delighted to have won a medal for the London event. ''I don't think l will do it again ... although I probably said that after the last one.''

Craig Brown, manager of the Scottish football team, was also there - but only as a spectator - as the runners set off from Blackheath. He had been in London for the Arsenal-Everton game and had a flight booked for Glasgow to meet up with the Scottish team at East Kilbride.

''Having had five knee operations, I don't think it would be a good idea for me to be out pounding the streets of London,'' he said.

Derartu Tulu has alert officials to thank for the cheque she collected yesterday for her victory.

Less than 20 yards from the finish of the race, the Ethiopian was almost felled by one of two publicity-seeking spectators, reportedly attempting to collect on a #300 bet.

The culprit was pounced on and almost flattened by David Bedford, race director, and Rob Smeaton, a security man, when within just one stride of bringing down the Ethiopian Olympic 10,000 metres champion.

''If I had fallen then, I would not have won the race,'' said Tulu afterwards.

Just 20 yards behind, and closing fast, was the Russian, Svetlana Sakharova.

Last night, a race spokesman confirmed that there had been one fatality during the event.

A man, whom organisers declined to identify, collapsed at the finish. He is believed to be the seventh fatality in the 20-year-history of the race.