The Joseph O'Brien-trained runner was the outsider of the seven-strong field and J J Slevin had him switched off at the back of the pack as Paul Townend set out to make all on 7-4 favourite Fabulous Saga.

The latter had built up a substantial lead and was still five lengths clear with three to jump, but Dicey O'Reilly was leading the chase and Fabulous Saga was clearly out of gas coming to the last.

It looked as though Jetz had stolen the advantage up the inside, but Slevin delivered the 25-1 winner down the middle of the track on the run to the line and Tower Bridge kept responding, eventually shading it on the line.

Slevin, winning his first Grade One, said: "It's great to get the chance to ride those horses, it's unbelievable really.

"Joseph clearly knows what he's doing and it was a big call to run a maiden in a race like that. His form over hurdles was solid.

"He won well. He travelled well and jumped well, he stuck his neck out well and galloped all the way to the line."

O'Brien said: "He was a good bumper horse and never jumped a hurdle in Down Royal one day and then jumped better the last day here. I think he only missed the first today.

"To be honest we were hoping to just get some prize-money today and go back and win our maiden in a couple of weeks. It's nice that he's done that today, and he should be better on better ground.

"He picked up from the second-last and galloped all the way to line.

"I'm delighted for J J who does a great job for us and gave him a great ride."

Jessica Harrington said of Jetz: "I'm absolutely thrilled, he was keen enough early on but when he was headed he battled back.

"The better going suited him and he'll be going to Fairyhouse and Punchestown. He's a chaser for next year."