I've really gone and done it this time. Last month, when I rolled the trailer, it was on soft grass. The dog bounced out wagging its tail and I brushed the grass off the buggy. I've been taking it easy with the trailer since that first incident, and this time, I really didn't think it should have tipped on to one wheel and then right over, but it did.

I was at the front of a large group of cyclists. One minute I was turning right, with a long pedalling column following. The next, there were shouts. I braked.

Everyone else braked, then stood around like voyeurs watching paramedics at the scene of a crash. The side of the buggy was badly ripped from being dragged along the road. I righted the trailer and the dog (again) bounced out wagging its tail, wondering what fun next. Phew. My wife was uncharacteristically reserved. “I told you that would happen.”

I felt unjustly wronged. There really was no justice in the trailer rolling. Me: “I was going really slowly!” (True.) My wife: “But you turned the corner too sharply.” (Also true.) “You have GOT to be more careful!”. I knew I only got off so lightly thanks to the audience. Sewing 12 inches of torn buggy canvas is a small price to pay.

We'd met in a sunny Broad Street on Sunday morning to ride to Blenheim Palace for the cycling festival. We took Sustrans Route 5 to Woodstock, north up the towpath via Wolvercote, under the A40 and on to the A44 south of Yarnton. It's a joy of a route, a remarkably quiet and civilised way of avoiding the Peartree roundabout. From Yarnton, there are decent cycle paths alongside the A44 to Woodstock. We arrived just in time for the start of the World Brompton Championship. Brompton make the world's coolest folding bikes.

There were a staggering 500 competitors in the race. Racers loitered in pens next to where their Bromptons sat, all folded up like praying machines. In gaggles of 50, they would run on the gun, assemble their folders as fast as possible and get going. Racers have to wear proper office clothing and prizes were given for the fastest as well as the best dressed. The men raced in suit jackets and tailored shorts, the women slacks with blouses. You have to pinch yourself at the sight of hundreds of eccentrically-dressed riders puffing and panting their way around the Duke of Marlborough's front garden — all on folding bikes with miniature wheels.

I hadn't realised what an international event it was until I met some Swedes who'd competed. Last year's was in Barcelona, and perhaps riding on the crest of that wave, a Catalan team won the fastest team and fastest male categories on Sunday.

The track was four miles long and the competitors did two laps. The course was then opened up to the spectators. We cruised around — a wonderful way of enjoying the Duke's estate. Rare too — bikes are otherwise banned in Blenheim's grounds.

The ride home was a killer. After 20 miles, towing a trailer feels like riding with the brakes on. I so need to get fit — and the 2009 World Brompton Championship, wherever it may be, seems like the perfect target to strive for. All I need now is a Brompton.