The two-mile race was between Petrosian and 11-10 favourite Sambulando before the latter decanted Sam Thomas at the third-last, leaving Petrosian all alone in front.

But he fell at the penultimate fence and Robert Thornton aboard Manorson (11-2) caught up and finished a distance clear.

Byron Moorcroft jumped back aboard Petrosian to finish second – an action he would not have been able to do next month following new British Horseracing Authority regulations.

O’Neill confirmed Manorson had been put down.

“Sadly we’ve lost him,” he said. “He had had his problems and I didn’t know him very well – I had only had him about a month. He was a grand little horse, so it’s a shame.”

Richard Johnson had ridden without success at both the previous two jumps fixtures at the Welsh outpost but notched a quick double for his main trainer Philip Hobbs.

It started with 7-4 favourite Calusa Caldera, whose jumping won him a Betfair Novices’ Chase depleted by the withdrawal of three of the seven declared.

The gelding had a few shots at fences without success last season but got it right this time to come home five lengths clear of Beautiful Vision.

Trainer Philip Hobbs said: “There’s another race exactly the same as this at Fontwell next Sunday that we’ll look at.”

The team’s 5-4 favourite Balthazar King made up for a fair few spurned opportunities by holding 33-1 shot Comehomequietly in the Iwec International Ltd “National Hunt” Maiden Hurdle.

Hobbs continued: “He probably wants a bit further, and he will jump fences at one point, but we’ll see how his next run over hurdles goes.”

Johnson later put the seal on a red-letter day when Cresswell Pride, trained by Keith Goldsworthy, landed the concluding bumper in some style.

The most valuable race of the day, the Integral Geotechnique Handicap Hurdle, went to local trainer Alison Thorpe as Treaty Flyer made it a hat-trick of wins under claimer Johnny Farrelly.

The 5-1 scorer is now bound for the Doncaster Sales.

Palmito (8-1) was Paddy Brennan’s first Ffos Las winner as she ran rings around her rivals to land the Haven Crane & Plant Hire Mares’ “National Hunt” Maiden Hurdle.

There was further chaos in the Paul Berkley-Smith Steam Event Management Conditional Jockeys’ Handicap Chase as Particle refused to jump the last when well clear, allowing Illogical Hope (11-4) to seize the advantage.

Particle’s rider, Donal Devereux, was given a six-day suspension for using his whip with excessive frequency.

Devereux was also banned one more day for hitting his horse in annoyance.

The jockey will be suspended on October 25 and October 28 – November 2.