There are some who say that the Grand National has lost its soul, that it is now a race for powerhouse stables and elite, big-money owners, not the dreamers and windmill-tilters that helped to make it the People’s Race. But it seems that the news has yet to reach the small stable in Newmarket where Michael Keady prepares Horantzau d’Airy, the eight-year-old gelding that will head to Aintree on Saturday afternoon as a 100-1 chance to win the National, for a trainer who has yet to saddle a single winner over jumps.

There are no end of plotlines in the story of Horantzau d’Airy’s path to Liverpool that would ensure the film script would write itself if he could somehow join the list of National winners at three-figure odds this weekend.

Keady has held a trainer’s licence for less than six months, his yard is in the Flat-racing fortress of Newmarket, which has not sent a National winner to Aintree for nearly a century, while Keady’s girlfriend, Ruth, who rides Horantzau d’Airy on the gallops every morning, is a native of Formby, just a dozen miles from the track.

And then there is the “click-and-buy” aspect of his unlikely journey, from Willie Mullins’s all-conquering jumping yard in County Carlow to a corner of East Anglia, where he rubs shoulders with three-year-old Classic contenders on the gallops each morning.

It was not quite eBay or Vinted, but Horantzau d’Airy was bought on the web – complete with his National entry – for £50,000 at Tattersalls’ Online Sale in early March, leaving Keady with a problem that many of us would appreciate: how to arrange the delivery.

There was, he decided, only one option. “I could have got him over in a shared lorry,” Keady said this week, “but we bought him on a Thursday and he wouldn’t have arrived until the following Tuesday. I was obviously conscious that the Grand National was coming up pretty soon, so I wanted him back as soon as possible.

“I got back from Kempton at 11 on Thursday night, and we were booked on the half-seven ferry on Friday morning. We left at 1am, the head lad kindly drove to Holyhead and we went over to Willie Mullins’s to pick him up, and we were safely back in the yard on Saturday morning.”

Horantzau d’Airy arrived in Newmarket exactly four weeks before the National, and Keady is still coming to terms with the prospect of saddling a runner in the world’s most famous steeplechase.

“It doesn’t feel real sometimes when you’re talking to people about it,” he says. “Things come out of your mouth and it doesn’t quite sound like it’s your mouth, it’s a bit surreal for a lad that grew up 12 miles down the road from Newmarket racecourse.

“We’re an Irish family and the Grand National was always a big event in our house growing up, but no one in my family was involved in racing in any way so it’s not something you’d ever really envisage happening.

“But Dad and Grandad were always mad into their horse racing, I suppose that was the Irish in them that was drawn to that, and I always remember going down to the pub with Dad on Grand National Saturday to watch it with my brothers and sisters.

“I wish my grandads were around to see it, but my dad is, he lives over in Ireland now and him and Mum are coming over for the race, and most of the family will be there, to try to make it a family affair on the other end of the scale this time.”

Flat racing’s spiritual home has swung behind its unexpected challenge for jumping’s biggest event, with the Jockey Club, which owns Newmarket’s famous gallops, going as far as setting up a replica Aintree fence to give Horantzau d’Airy a sighter of what to expect on Saturday.

“They very kindly put up a fence and they weren’t shy in doing it,” he says. “It was a pretty big one. Ciarán Gethings [Horantzau d’Airy’s big-race jockey] came in and jumped it and said they wouldn’t be as big as that around Aintree. He won the Topham [over the National fences] last year, so he knows his way around. It was a good test and he passed with flying colours.”

Keady’s gelding is, as you would expect, something of a novelty around Newmarket, where the Classic prospects are emerging from their winter slumber to find a strapping steeplechaser in their midst.

“There’s about 5,000 horses here and probably no more than 100 of those are jumpers,” he says. “He’s a big boy and he does stand out a bit. Every morning where we’re riding out, people are asking where he is, but it doesn’t take long to realise. He’s about a hand bigger than anything else.”

Horantzau d’Airy’s preparation, meanwhile, has gone without a hitch. “He had a bit of a lung infection, which we sorted out, and in the last 10 days or two weeks, he’s started to come alive,” Keady says.

“I don’t think anyone will ever take a horse from Willie Mullins and improve it, but if we can just get him back to his best, I wouldn’t put him far away from running a big race.

“You never know with the Grand National, and you’ve got to be in it to win it. Someone said to me the other day, you’ve bought your lottery ticket, so we’ll see where we are at about 4.15 on Saturday afternoon.”