The £50m tumble – how Annie's power outage saved the bookies

It was all so easy on the opening day of the 2015 Cheltenham Festival. Douvan, Un De Sceaux, Faugheen. Bang, bang, bang for Willie Mullins. Punters in paradise after three races. Layers in lava.

“The four-timer is on,” screamed course commentator Ian Bartlett as Annie Power swung for home three lengths clear in the OLBG Mares' Hurdle, the next race on the card. The bookmaking industry was about to take a £50 million bullet. She was a stout stayer, an electric jumper and officially rated 7lb clear of anything else. What could possibly go wrong?

But this is the world of horseracing, and just as punters had begun to add up how much their accumulators were paying, Annie Power took off a stride too early at the last and knuckled on landing. She was gone. Audible gasps of disbelief swirled around the enclosures. Curses were invented. It was agony for punters, ecstasy for bookies. The layers had lost three bruising battles but won the war.

“It was one of the strangest feelings coming down from the stands,” Mullins recalled. “I thought the worst thing that could have possibly happened, did happen. The unthinkable. Annie took the most horrific fall and I feared the worst. The green curtains were up and I had no idea what was happening behind them."

Mullins' other runner, Glens Melody, was involved in a tight photo-finish with Polly Peachum and the trainer feared the worst there too. “I had one mare behind green curtains after an almighty fall and another that had got chinned on the line. I was completely down in the dumps. It was the lowest I had been in a long time."

He added: “The next 60 seconds or so were remarkable, though. Someone informed me Annie Power was running loose, not a bother on her, and then the result of the photo-finish was announced. Glens Melody had won and I was absolutely thrilled for Fiona [McStay, her owner]. It’s amazing how quickly your mood can change in the matter of a few seconds.”

The mood among bookmakers changed rapidly too. “We consider it to be the £50m fall,” said Ladbrokes' spokesman David Williams. “We’d have been facing up to the worst day since ‘Dettori Day’. As it is, we’ve dodged the most expensive bullet we’ve ever faced. The God of bookmaking moves in mysterious ways.”

How Annie Power came to grief remains a mystery but it was one of only two blips in a quite brilliant career.