The pair proved firm punters’ favourites with a string of recent wins, forcing Paddy Power to downgrade profit expectations from e82million (£68million) to e75million for the full year.

Shares in the London-listed Irish group lost e0.85 to e15.2. Pre-tax profits rose 10 per cent to e47.1million for the six months to June but the damage was done in the past two months.

The credit crunch also slowed growth, warned chief executive Patrick Kennedy, but special offers gained the firm market share.

Kennedy said O’Brien and Harrington did a lot of damage: “It’s the old adage — some you win, some you lose.”

He said the company was going ahead with plans to expand its UK chain from 67 shops to 150 by the end of 2011. It has 186 in Ireland.