Defiant Radcliffe at crossroads

"Why would Beijing be ruled out?" she asked incredulously. "It is more likely that it is somewhere where I would like to be. But it is obviously three years ahead and I can't say 100 per cent I will be there."

Athens, where she failed to finish the 10,000m as well as the marathon following stomach problems, has clearly left mental scars which may never completely heal.

She said: "You put it out of your mind. But when you look back at it, you are never going to look back and laugh. You are always going to look back and think, 'Why couldn't everything go right for an Olympics?'. That's natural. But I believe I can get back to that level of two years ago. Of course I can."

Clearly the health problems need to be sorted out to achieve that, given that she regularly prepares for marathons with 10 weeks of tough altitude training in New Mexico.

Pasta, the pre-race petrol of most marathon runners, is off the menu as Radcliffe attempts to find the foods which are causing her problems.

She has taken wheat, gluten and dairy products out of her diet since Athens and is experimenting with foods to try to find the substances which her body cannot tolerate. Sausages are clearly okay at the moment, but Radcliffe leaves half of one untouched and she would not win awards for clearing her plate.

Asked if she feared it might be a long-term problem, she said: "I wish I had found out sooner because I probably do have some intolerances to some things but it is not all of them. I don't find it a problem, to be honest. Once I find out what it is and avoid it, it will be well worth it."

She is also learning how to stomach criticism better, which has been especially important this week following comments by Liz McColgan, her predecessor as Britain's greatest woman distance runner. The Scot suggested Radcliffe had passed her best and might not make it to Beijing.

Radcliffe countered: "You are never going to please everybody all of the time. It was hard for me. I used to worry about the five per cent of people that weren't happy about what I was doing, instead of thinking of the 95 per cent who were.

I accept there is going to be criticism. You have to turn a blind eye to it. I probably let it get to me too much before."

As for being over the hill, she said: "Everybody gets older. But there are also things as an athlete where you get wiser. Haile Gebrselassie towards the end of his career knew he wasn't going to run faster than the world record but he was still winning races and championships.

You get other strengths with age. My endurance is better and you become more mellow and less in a rush to try and fit everything in."

Radcliffe is yet to decide whether to run the 10,000m or the marathon at the world championships in August as she bids to win the global title that has eluded her despite gold medals at European and Commonwealth level. The competition in the Finnish capital is likely to be more fierce on the track than on the roads.

She said: "The problem is I want to do them both. Making the decision to let one go is hard. If I felt I would not have a chance over 10,000m, it would be easier. But I honestly believe if I can get into the shape I was in last year for Gateshead [in June], then that will be good enough to win it.

"The 10,000m is first this time so it is more possible than the other way around to do both. But it is more important to come out with one gold medal."

In the long-term the most eloquent female figure in British athletics is keen on coaching and being a mentor to younger athletes.

She said: "You learn things and I would like to help somebody and warn them about some things. Dave Moorcroft mentored me when I was younger. I would also like to do more on anti-doping but those things have to wait until I have the time."

Her best role could be as a senior figure in the IAAF, the governing body of athletics, or in the International Olympic Committee, which is desperately looking for former female athletes to take up responsibilities.

For now Radcliffe is happy to pick up an appearance fee of half a million dollars in London. She could double her money in bonuses if she wins inside her 2002 time of 2hr 18min 56sec - run without the male pacemakers of the 2003 race.

A field including Kenya's Margaret Okayo, the defending champion, and Susan Chepkemei, who pushed Radcliffe to the line in November's New York Marathon, will make the race far from easy for Radcliffe.