Marie’s Rock gave Nicky Henderson and Nico de Boinville gave a big-race double by springing a surprise in the Close Brothers Mares’ Hurdle at Cheltenham.

The 18-1 shot, owned by Middleham Park Racing, collared Queens Brook up the hill to win a dramatic renewal of the Grade One contest over two and a half miles.

There was all to play for when Indefatigable fell at the second-last flight, bringing down Telmesomethinggirl, for the Honeysuckle connections of owner Kenny Alexander, trainer Henry de Bromhead and jockey Rachael Blackmore.

Queens Brook was left in the lead but she was soon hard pressed by Marie's Rock, who proved the stronger to get the verdict by a length and three-quarters. Mrs Milner was the same distance away despite being hampered by the melee at the penultimate hurdle.

The victory was the second leg of a brace for Nicky Henderson and Nico De Boinville after Constitution Hill in the Supreme Novices' Hurdle.

De Boinville said: "She's such a gutsy mare, the boss has had to be quite patient with her as she didn't really find her stride last year.

"She's just come into her own today, that was fantastic."

Tim Palin, of the Middleham Park Racing syndicate that own the seven-year-old, said: "I'm thrilled for all these owners and Nicky Henderson, what a genius.

"She was in the wilderness for 12 months. She was favourite for the mares' novice, got injured and then we lost her, but he's a genius.

"She spent some time off in a field and came in a different horse and then it's been onwards and upwards.

"We've had a winner here before with Junior in the Kim Muir but this is our first Grade One over jumps, never mind here, and she only cost £35,000."

Henderson said: "This is fantastic because we lost her last year, a bit like Epatante, she went walkabout – it's lovely when they come back.

"I was very impressed with her when she won at Warwick last time out so I was hopeful, but I knew it would be very competitive.

"Winning the first race takes the pressure off, we can enjoy it all now."