My First Job: The television journalist Jonathan Dimbleby was a professional showjumper

'I was often in the money'

Jonathan Dimbleby was tipped for stardom when he was 20 - by Horse & Hound. But the horsey magazine wasn't prophesying his glittering career as a radio and television presenter and documentary maker. No, H&H saw him as a future star of British showjumping. And, indeed, 40 years ago, when he was 21, Jonathan did become the South of England showjumping champion. As he says now, "What's the odd Bafta after that?".

With his brother David, Jonathan spent much of his childhood on the family's 25-acre smallholding. "I had a passion for horses and, in particular, showjumping. I left school after my A-levels and worked as a student on a farm outside Windsor, then did a farm-management course at agricultural college in Cirencester."

He would also drive to a stables in Sussex to work with the horses; it was here that he went on to spend 18 months, working seven days a week, riding horses.

"On a show day, I would get up at 5am to wash, clean and groom the horses, plait their tails and, if they had 'white socks', rub white chalk on their legs. I would load up three horses and drive to the showground for the competition, getting increasingly tense. Knock just one fence down and you're out. But I would often be 'in the money', that is, in the top five winning the (small) awards."

A win would increase the value of the horse. Len Carter, the stables' owner, had a fierce temper: "He would hit my legs with his whip. The third time he did it, I said, 'If you do that again, I'll hit you as hard as I can'. He was in his seventies and never did it again."

Jonathan was equally struck by Len's habit, after making a sale (and downing a few glasses of whisky) of saying to the purchaser, "I'll toss you for the horse - double or nothing". This meant that a buyer got a free horse if he won, but had to pay twice as much if he lost. Alternatively, they could toss the coin again. On one occasion, £4,000 was riding on the bet: "The coin fell in some mud - upright!" They stopped horsing around and the purchaser paid just the original £1,000.

After a fascinating year and a half, Jonathan, shaken by the death from cancer of his father [the broadcaster Richard Dimbleby], decided to leave the equine world and go to university instead, thereby cutting short the starry showjumping career that Horse & Hound had confidently predicted for him.

'The Big Behaviour Debate', chaired by Jonathan Dimbleby, is on the Teachers' TV channel on 4 September

jonty@jonathansale.com