As a start to a new career goes it is difficult to imagine anyone matching former champion Flat jockey Joseph O’Brien’s four-timer from six runners on his first day as a fully-fledged trainer.

Justice Frederick got the ball rolling by winning the Irish Stallion Farms EBF Maiden at Gowran Park, which was swiftly followed up when Mai Fitzs Jack strolled home in the John B. Keane (C & G) Maiden Hurdle at Listowel.

The third success came back on the level with O’Brien’s brother, Donnacha, who also rode Justice Frederick, coming from nearly last on Zig Zag in the Gowran Park Golf Club Handicap.

O’Brien’s sister, Sarah, meanwhile, merely had to point Oathkeeper in the right direction to take the concluding bumper at Listowel, fairly bolting up in the colours of JP McManus.

Multiple Classic winner O’Brien has been overseeing a team of horses at his family’s Piltown yard, but until he completed all his training modules they were competing under the name of his father, Aidan.

To prove how seriously he is taking his new venture the fledgling trainer was sourcing new horses at the sales rather than watching any of his current ones run in person.

Justice Frederick had been an odds-on favourite in the morning with a newcomer from O’Brien senior’s Ballydoyle base, Leo Minor, easily backable.

However, right on the off there was a huge shift in momentum which saw Leo Minor go off favourite at 6-5 and Justice Frederick sent off at 6-4.

Leo Minor came with a challenge but looked green on his debut and was beaten a length and a half, with the success coming 23 years after Aidan O’Brien saddled his first winner, Wandering Thoughts, at Tralee.

Donnacha O’Brien said: “He learned from the first day, and the step up to seven furlongs suited him.”

Annemarie O’Brien, Joseph’s mother, added: “The plan is to go for the Chesham at Royal Ascot.”

Mai Fitzs Jack won as an odds-on shot should. Made the 4-9 favourite on the strength of a second-place finish last time out, the result hardly looked in any doubt.

Brian O’Connell never had to exert himself and just had to keep his wits about him as his mount got in slightly too close to the final flight.

Aidan O’Brien was at Listowel, where he said: “Straight away I got put in my place!

“It was great in Gowran and our own horse (runner-up Leo Minor) maybe got a little tired and I underestimated the strength of Joseph’s horse, obviously.

“His (Joseph’s winner Justice Frederick) first run was over five (furlongs) and is a horse that will get seven and further.

“This horse (Mai Fitzs Jack) was unlucky the last day when he made a mistake at the last two and I think the winner was a decent horse.

“I’m not sure, but I’d imagine he’ll (Joseph) keep him busy over the summer.”

He went on: “It’s a massive day for us and it’s great to get a win both over jumps and on the Flat.

“I couldn’t believe when someone said to me that it was 23 years ago to the meeting (then at Tralee) that I had my first winner with Wandering Thoughts — I couldn’t believe that, it is some coincidence.

“Joseph loves it (training) — he loved riding but it was tough for him for a long time (with weight); doing 9st every morning was very hard.

“He’s a big man now, he’s well over 11st and he doesn’t look heavy.

“No one will get more pleasure than me, but I’ll have to keep my eye on the ball now!”

Zig Zag (7-1) weaved through nearly the whole field for his success, with Annemarie O’Brien saying: “It’s been a great day for Joseph, and it’s nice to get a bracket for this horse. He’ll go for something similar again.

“I thought Ana’s horse (O’Brien on No Biggie) was coming there to win, and didn’t really notice Donnacha until late on. He got a nice run up the rail and finished well.”

Oathkeeper could not have done it any easier as the 11-8 favourite, coming home with nine lengths in hand of Bel Sas.

Aidan O’Brien said: “It’s very exciting and great also for JP. It (Joseph’s career) is something to look forward to and he looks a fair horse.

“I think he might be going jumping now, but Joseph will discuss that with Frank (Berry, McManus’ racing manager).

“It has been an incredible day and how can you improve on that!”