He has been a professional footballer, an FA Cup-winning manager and the King of the Jungle over the storied course of the past 60 years, but as Harry Redknapp talked about The Jukebox Man, his King George VI Chase contender, at Ben Pauling’s stable last week, he was the East End kid whose nan was a bookie’s runner and would be astonished to see where life and luck have taken her grandson.

“She wouldn’t believe it,” Redknapp says, suddenly back in Poplar in the 1950s. “It’s a far cry from the East End of London, [when she was] getting slung in the back of a police van every other day for collecting the bets.

“People forget there were no betting shops, betting was totally illegal, so the only way you could have a bet was through an illegal bookmaker. Cyril the paperboy, he wasn’t a boy, he was about 70, but everyone still called him the paperboy. He was the bookmaker, my nan would take the bets and Cyril would take them and pay out the next day.

“Three tuppenny doubles and a tuppenny treble, that was the standard bet, and the only way you got the results was sitting round the radio at six o’clock at night. They’d call the results out and she’d scribble them down so she knew who’d won and who’d lost.”

There is a distinct sense that Redknapp still can’t quite believe it himself. He is not a celebrity racehorse owner, dabbling in the game until something else takes their fancy. He is a racehorse owner who happens to be a celebrity, a lifelong fan who has done the hard yards in ownership for the past 40 years, swallowed the disappointments and bounced back for more.

He now has a horse that is good enough to line up for one of the most famous steeplechases in the calendar. Arkle, Wayward Lad, Desert Orchid and Kauto Star are among the chasing legends on the King George’s roll of honour and even in what is being seen as the strongest field for years The Jukebox Man is a live 6-1 shot.

“I’ve loved the racing all my life, really,” Redknapp says, “but [in the 50s and 60s] going racing wasn’t something we ever did. As a player at West Ham, we were full of punters, all boys out of the same area from within six or seven miles of the ground probably, and most of us loved a bet, but it was dog racing.

“We’d go to Walthamstow on a Friday night and Hackney Wick. We’d all be into it, but horse racing was another world away from us in east London. It was only when I went to Bournemouth [in the late 1980s] that I got involved in my first horse. There were seven of us, I think, in the syndicate, a couple of vice-presidents and one of the directors. We all put in a grand each and bought a horse with David Elsworth, Slick Cherry.”

Desert Orchid, perhaps the greatest King George legend of all, was among Slick Cherry’s stable companions. While her 6-1 success – after plenty of support – in a Windsor maiden in July 1990 went unnoticed at the time, Redknapp’s ownership career was off and running. There have been dozens of runners in his colours since then, on the Flat and over jumps, and enough good days among the let-downs to keep Redknapp firmly on the hook.

The best moment – so far – was a win for Shakem Up’Arry at last year’s Cheltenham festival, which made The Jukebox Man’s narrow defeat at the meeting 24 hours later after leading over the final flight a little easier to bear.

“I do lay in bed dreaming about him jumping the last at Kempton, taking it up and going clear,” Redknapp says, “but not the day he jumped the last at Cheltenham five lengths clear and the horse he’d gone away from suddenly started to close the gap.

“I don’t know how I’d have felt if Shakem Up’Arry hadn’t won the day before. It was like being two up going into extra time, the fourth official’s put up three minutes and suddenly, bang, bang, the dream’s gone.”

Sandra, Redknapp’s wife, who joined him on the visit to Pauling’s west-country yard, has long since learned to live with her husband’s hobby. “I think sometimes he doesn’t tell me [when he buys another horse]. I’ll say, ‘when did you buy that one, then?’ and he’ll say ‘oooh, ages ago …”

Harry recalls her reaction to a recent report on The Jukebox Man. “A guy on the TV said, ‘Harry Redknapp, he keeps buying horses and he never buys a bad one’, and Sandra fell off the settee laughing. We’ve got a list as long as your arm so when you get a good one you’ve got to enjoy it.”

Sandra will make a rare trip to the races on Friday to watch The Jukebox Man attempt to repeat his Grade One win over the King George distance in a novice chase on Boxing Day 12 months ago. “It’s like going into the Champions League,” Redknapp says. “You look at the teams that are still in it and you think, my God, but you still think you’ve got a chance and you’re dreaming that you could go all the way and win it.

“He’s not favourite, but he goes there with a chance, and if he’s improving like Ben thinks he is he’s got a real chance.”