Punters floored the bookmakers with a string of well-backed winners on day three of the Cheltenham Festival.

The layers just about held the edge at the halfway stage and had a false dawn in the opener on Thursday when 4-9 favourite Envoi Allen, one of the bankers of the week, was an early casualty in the Marsh Novices’ Chase.

His exit blew the race wide open and it was left to the Nicky Henderson-trained Chantry House (9-1) to land the spoils.

One punter who was happy he decided not to pin half a million hopes on Envoi Allen was Betfair client Paul Dean. He partially cashed out for £250,000 after all the previous legs of his £5 accumulator had won.

The layers had another narrow escape when 100-30 favourite The Bosses Oscar had to play second fiddle to Mrs Milner (12-1) in the Pertemps Network Final Handicap Hurdle.

But then the tide turned with Allaho (3-1 favourite) justifying strong support in the Ryanair Chase for Willie Mullins and Rachael Blackmore.

The Shunter (9-4 favourite) was probably the best-backed winner in the Paddy Power Plate, while Telmesomethinggirl (5-1) was another popular one for the irrepressible Blackmore in the Parnell Properties Mares’ Novices’ Hurdle.

The defeat of 9-4 favourite Paisley Park in the Paddy Power Stayers’ Hurdle, won by Flooring Porter (12-1), did little to cheer the bookmakers, while the incredible last-to-first dash of Mount Ida (3-1 favourite) in the Fulke Walwyn Kim Muir Challenge Cup summed up their day.

“Envoi Allen’s defeat in the Marsh ended the run of opening-race winning favourites this week, while the ever popular Paisley Park could manage only third place in the Stayers’ Hurdle,” said Coral’s David Stevens.

“But if they were the highlights for us, plenty of punters cheered home two more winners for the in-form Rachael Blackmore in Allaho and Telmesomethinggirl, while The Shunter landed one of the gambles of the week in the Plate.

“With the biggest day of the week to come, there’s still all to play for in this stay at home Festival, with Blackmore’s mount, A Plus Tard, likely to prove extremely popular in the WellChild Cheltenham Gold Cup betting – to the point where the duo could even be sent off favourite in place of the hat-trick-seeking Al Boum Photo.”

Paddy Power spokesman Paul Binfield said: “That was a shocker of a day for the bookies with a string of bad results including the smashed-up The Shunter and Mount Ida in the lucky last.

“We were winning yesterday, but we’re down on the week now and need a good Gold Cup day to recover.”

Betway’s Chad Yeomans summed up the feelings of the layers.

“After a good opening two days for us, the punters have definitely had the edge today. It’s very quiet in on the trading room floor right now,” he said.

“It was sad to see Envoi Allen over-jump and not make it round. We’re all here to watch fantastic racing and we were starved of that in the opener. It was brilliant to see him get straight up though and he’ll have another day – or many other days – to earn punters their cash back.

“The Shunter, Telmesomethinggirl and Mount Ida were our three biggest losing results of the day, so when they all were victories in the last three races, it meant for a bad afternoon. The pendulum has swung in the punters’ favour going into day four.”