Rebecca Tyrrel: 'The patriotic Olympic nappy has the Union Jack emblazoned upon its rear

Who knew that Paula Radcliffe had it in her to brazen out her new role as Olympic frontwoman for Pampers nappies while ignoring the obvious irony? Somehow she has done just that. Radcliffe has posed for photo-shoots and made promotional films with her infant son modelling the GB Design Active Fit nappy, without a single raised eyebrow or knowing smirk about her own legendary lavatory stop.

It is sad that Radcliffe is the source of such infantile mirth among sporting ignorami like myself, whose knowledge of her achievements is limited to one embarrassing incident (though to her credit she has never seemed remotely embarrassed herself). To those who care about such things, she is the remarkable endurance athlete who has won the marathon in Chicago, New York (twice) and London (thrice), holds the world record for the event, and was even voted BBC Sports Personality of the Year in 2002.

Yet seven years after that infamous 'comfort break' during the 2005 London Marathon, when she squatted by the road before continuing and winning the race, she remains best known to the general public for suffering, the year before, what she called "the dreaded runner's diarrhoea". We are still chortling about it today.

She is not, however. And without the vaguest nod or wink to the incident, she is spearheading an advertising drive for Pampers. This beguilingly patriotic Olympic nappy has the Union Jack emblazoned upon its rear, and while one wonders about the subliminal messaging, we hope this is no omen for the dumping of medal hopes in the summer.

We must admire her for the bold endorsement, not only of the product, but also of the old adage 'where there's muck, there's brass'. And no one could question Radcliffe's genuine faith in Pampers.

"I really do use them and I really do believe in them. They're a great product," she says in the promotional literature, before admiring the increased mobility the nappy offers toddlers like her own: "I understand the importance of having the right kit to help me achieve my athletic potential". The chafing over-26-and-a-bit miles may not bear imagining, but it is tempting to wonder if Radcliffe isn't quite a comic talent, and that she will be the one secretly laughing all the way to the finish line. Not to mention the bank.