I FOUND myself stranded and helpless on a dual carriageway somewhere between West London and Oxford the other day, looking for a place to bury my bike.

I had decided to accompany Jane Tomlinson, the mother of three, who is close to the finishing stages of a 2,000-mile bike ride from Rome to her home in Leeds, in spite of suffering from an incurable cancer.

I dusted down my bicycle and reminded myself I had done many a charity bike hike in the days before I had become too fat for my tracksuit.

I met her and her brother, Luke Goward, in a Travel Inn in Hayes, Middlesex, and I felt comforted by her nonchalance about the day's trip. "It'll be like a nice day out, just a tootle along," she said, making it sound like a school outing.

I naively believed her, though I should have understood those words in the context of her ultra-fitness. She has run three marathons and completed a triathlon in two years. I, for my part, have put on a stone and given up my twice-weekly spinning classes during that time.

But, ever the optimist, I jumped on my mountain bike and tore down the road with glory-filled thoughts of arriving in Oxford by tea-time and boasting to all my friends about the accomplishment.

I kept up with the tandem for the first half hour but only because we were on a perilously narrow tow-path. But once the tandem was unleashed on the dual carriageways of the home counties, I woke up to the reality of pedalling 48 miles with two people who had been cycling up to 70 miles a day for the past month.

They gradually went from being ten metres ahead of me to becoming a spot in the distance, until they disappeared out of view. And that's when the navigational trouble began.

For reassurance, I had kept chanting the name of the road that Jane had said to follow until I came to Marlow, where we would meet for lunch. "Just keep following the A308, and you'll get there," she'd said. And so I would have done if I hadn't taken the A308 in the opposite direction.

Eight miles later, the penny dropped and I began terrifying a workman with my tears. He gave me his road atlas and told me I couldn't go wrong if I just followed the thick red line. Another five miles later, equally as lost, I conceded to altas dyslexia and was hatching a plan to get a cab up to Oxford.

I crawled up the road and wondered whether I'd make it to the next town before the light faded. By then, I had begun giving the motorists helpless stares as I languished by the roadside, in the hope they would stop and scoop me into their comfy cars.

Humiliated and defeated, I finally gave in and was reunited with Jane by taxi. At least I had managed to cycle about 35 miles, she said, even if half of that was going round in a circle.