City Island provided the Mulryan family with a famous success in the Ballymore Novices' Hurdle at Cheltenham.
Sean Mulryan founded the Ballymore Properties Group, and City Island runs in the colours of his wife Bernadette.
The six-year-old has been brought along steadily by Martin Brassil, who trained Grand National winner Numbersixvalverde in 2006, and was facing by far his stiffest test to date.
Ridden by Tuesday's Champion Hurdle hero Mark Walsh, the only moment of worry came on the approach to the second-last when City Island went for a gap between Sams Profile and Valdieu - but he made it just in time.
Into the straight, it only concerned two - Champ coming clear with the 8-1 winner, but Nicky Henderson's 9-2 chance gave way after the last with City Island a two-length winner.
Ben Pauling's Bright Forecast stayed on for third, just ahead of Brewin'upastorm.
A delighted Mulryan said: "The heartbeat is very high - it's a dream come true. He won in Galway and we said we'd aim for this race. We're absolutely ecstatic. I thought he wasn't enjoying the ground, but the way he finished the race was fantastic."
It was a landmark first Festival winner for Brassil.
He said: "It's been a long time coming. You need good horses to bring here. We found one. The thought I had was you bring a horse here thinking he's unbeatable and you might have a chance of him doing something good then. It's great to have a Festival winner on your CV."