Demure, and so softly spoken that even my Philips 860 Voice Tracer strains to pick up her words, Paula Radcliffe is nevertheless possessed of a disconcertingly direct, unflinching gaze, holding my eyes with hers for the entire 45 minutes of our encounter. It is the only outward manifestation of the ferocity of her drive, the unquenchability of her spirit. And she is looking forward to next year's Olympic Games in much the same way, with an almost scarily intense, unyielding focus. As she says herself, everything she does "is a stepping stone to London 2012, everything is working back from that".
The first major stepping stone was meant to be next weekend's Great Manchester Run, the race she and her husband and coach, Gary Lough, had earmarked as her return to competitive running after a break of almost 18 months, during which she gave birth to their second child, Raphael.
But earlier this week she withdrew, citing a chest and throat infection. And so it is her non-participation that becomes a stepping stone towards the Olympic marathon on 5 August next year: her preparation, even now, is so finely calibrated that what she doesn't do is just as significant as what she does do. This is the world of Paula Radcliffe, whose marathon record of two hours, 15 minutes and 25 seconds, established in London, has now stood, without ever being seriously challenged, for more than eight years. It is no place for ordinary mortals, her world. Even her training regime might have been enshrined in the Book of Genesis. For seven days she runs, stretches, lifts weights, naps, runs some more. On the eighth day she rests.
It is the eighth day, and she is sitting in the lounge of the Intercontinental Hotel in London, picking at French fries. She would, I don't doubt for a second, greatly prefer to be pounding the roads near her home in Monaco, or in Albuquerque, New Mexico, whence she has just returned from a two-month training camp. But she is obliged to publicise her new coaching manual, How To Run, and so here we are, eyes locked on each other.
I ask her how she has stoked the competitive fires during so long out of competition. Table tennis? Scrabble? Speed nappy-changing? She gives a shy little laugh. "The competitive flame is just there, just there inside me. My career might come to an end one day but it won't be because I've lost the competitive spirit. It'll be because my body won't withstand the training it needs to race as well as I want to race."
The word "might" is the revealing one. Radcliffe is 37 now, yet seemingly can't quite bring herself to admit that retirement is not a matter of if, but when. I float the beguiling prospect of her at long last winning Olympic gold, which, in front of an overwhelmingly British crowd, after all the heartache in previous Games, would surely represent the perfect moment to hang up her singlet for good? "No," she says, equably. "I'm going to keep going as long as I can. I've had a very long career and I'm very grateful, but this is still what I most want to do."
With Manchester now scrubbed from her schedule, her return to competition – she prefers not to call it a comeback – is likely to take place at the end of this month in the London 10,000. She and Lough have been almost fearfully cautious about entering her for races again. "I rushed back a little too quickly after [her first child] Isla was born, and got injured, so this time we decided to take our time, and start with some shorter races now with a view to running really well in the autumn, and next year. At 10k I'm maybe not going to get back quite to where I was 10 years ago, but I still think I can be very competitive."
Radcliffe still looks as spare and sinewy as she did last time I met her, before she had children, but clearly her body has changed, and so I ask what effect two pregnancies have had on her running style.
"I think that when you go through childbirth, endurance-wise you get stronger," she says. "In fact, your endurance gets stronger as you get older. But they also say it takes nine months to a year for your pelvis to get back to where it was pre-pregnancy, so that changes your gait a bit, which is one of the reasons why I ended up with a stress fracture last time. I ramped up the mileage a little bit too much."
She blames that stress fracture of her left femur for disrupting her preparations for the 2008 Olympics. Four years earlier in Athens, as favourite for the gold medal, she had fallen victim to stomach cramps, apparently a consequence of taking anti-inflammatory tablets, and her withdrawal more than four miles from the finish caused her such acute and manifest distress that some viewers back home felt their sympathy waning, reasoning that she'd lost a race, not a child. But she wasn't a mother then, and for all the changes that motherhood has wrought to her body, the most seismic effect is psychological.
"If you'd asked me 10 years ago, I'd have said that I needed that Olympic medal, that it was about defining my career. But my perspective has changed. The most important thing for me now is that my children stay healthy. That doesn't mean I want to win the Olympics any less, just that it's no longer the most important thing. And that's not just me, it's anyone with children. They don't care if a training session has gone well or not."
All this presumably means that, notwithstanding the intensity of her ambition, if she doesn't win a gold medal next August – which, while yielding yet more Olympic disappointment, would in another sense be a first, for Radcliffe has never lost a marathon on the streets of London – we won't see emotional disintegration on the scale of 2004. And yet she makes no apology for her very public show of distress in Athens. Indeed, it still makes sense to her that the response to it drove her and Lough to set up home later that year in Monte Carlo, where they've been ever since.
"A lot of it was the fallout from Athens. I just didn't feel comfortable in this country. I felt I'd let a lot of people down. There were other reasons too. We love being in France, Monaco is very supportive of sport, it's a great place to bring up children, and it's a much easier drive to the Pyrenees, where I do altitude training. But I did struggle after Athens. A lot of people were... not vicious but very critical. Eventually I was able to heal myself by running again. And I'm good at letting my emotions out. I did a lot of crying after Athens, which got it out of my system. Gary, who bottles up his emotions, found it harder."
The pair knew only too well that, aged 30, and with her formidable world record just over a year old, the Athens marathon had in theory come at the perfect time for Radcliffe. She concedes that it's hard to say the same about 2012. "Yeah, on paper I've had a stronger chance in previous years. But in London, with all that atmosphere and support... and I know I can still run times capable of winning the event. I can definitely run a sub 2:20. Whether I can run sub-2:15 I don't know. I don't think it's impossible, but I don't think it will be necessary. I think 2:17 would do it."
She is not surprised, she adds, that her 2003 record endures. "When I became conscious in that race that I would break the world record, I put everything into it, knowing that someone would have to run very hard to beat it. Someone will, with all the advances in shoe technology, and race directors making courses faster, but it's nice to have it."
As long as it's beaten honestly, she won't mind too much. For all her natural shyness, Radcliffe has long been a forthright critic of drug cheats, and wants testing to be much more rigorous. She was last tested herself just a week before. "A urine test, at 7am. Before that, it was just after Christmas while I was staying with my mum and dad, who hadn't told me that the buzzer on the gate was broken. It was sheer luck that my mum looked out of the window and saw the lady waiting there. Otherwise they could have said it was a missed test."
She smiles, happy that they didn't, and happy with life. She'll be even happier when the eighth day closes, and she can get back to her seven-day cycle of doing what she does best.
'How To Run', by Paula Radcliffe (Simon & Schuster, £14.99)