What A Friend, trained by all-conquering handler Paul Nicholls and ridden by Sam Thomas, just held off Money Trix and Joncol to take the prize at odds of 11/2.
Thomas, who only got the ride because Barry Geraghty opted to ride at Newbury instead, was ecstatic to have won in what has been a difficult year for him which saw him jocked off another stable star Denman, on whom he had won the Cheltenham Gold Cup in 2008.
“If you take Denman out he would have been a good winner of the Hennessy and all credit to him for coming here three weeks after that run,” said Thomas.
“People thought he was ungenuine in the Hennessy (he was second to Denman) when he wandered about going to the final fence but he was just trying so hard.
“Some great horses like Denman and Beef Or Salmon have won this race so hopefully our horse can go onto bigger and better things and I think he might come back here for the Irish Hennessy.”
Bookmakers reacted to What A Friend's victory by cutting the six-year-old to 20-1 from 33s for the 2010 Cheltenham Gold Cup.
It was the biggest National Hunt win so far for Ferguson, who jointly owns the winner with Ged Mason.
He has enjoyed mixed fortunes during his forays into racehorse ownership.
Ferguson led in the brilliant flat horse Rock of Gibraltar (pictured) during his early successes, but an ownership dispute saw him come off second best in a row with wealthy Irish racing duo JP McManus and John Magnier.