AN estimated one third of the British betting shop industry's £100 million sterling annual profits were wiped out by jockey Frankie Dettori's unprecedented seven horse triumph at Ascot race course on Saturday.

Stanley Leisure, the fourth biggest bookmaker or betting shop chain, was forced to issue a profits warning as its losses reached £2.25 million after the race.

William Hill and Ladbroke, the two biggest bookmakers, are understood to have losses of about £8 million each, while Coral, the third biggest bookmaker, lost an estimated £4 million.

Bookmakers would normally regard losing £2 million on a big race as a bad result.

Mr Tom Kelly, director general of the Betting Office Licensees' Association, which represents 5,000 of the 8,800 British betting shops, said the total losses would have been higher if bookmakers did not have limits on payouts. This is generally £500,000 per bet among the bigger bookmakers, dropping to about £25,000 for smaller ones.

Mr Kelly said it was difficult to put an exact figure on the extent of the industry's losses but added: "It could be £30 million but could be higher still."

Gamblers backing the Italian born Mr Dettori to win all seven races saw their original bets multiply by the odds quoted on each horse every time he won. Faced with such a large number of accumulator bets on Mr Dettori, bookmakers were unable to pass the risks on to third parties, as they normally would.

Mr Dettori, who had become a punters' favourite even before Saturday's events, rode to victory on Wall Street at 2-1, Diffident at 12-1, Mark of Esteem at 100-30, Decorated Hero at 7-1, Fatefully, a 7-4 favourite, Lochangel, a 5-4 joint favourite, and Fujiyama Crest, a 2-1 favourite.

Some in the betting industry were putting a brave face on the upset. Mr Paul Olive, finance director of Stanley Leisure, said: "Despite the result, this is good PR for the industry and should stimulate more business in the long run." Coral's said: "This could actually be a shot in the arm for the industry after the National Lottery."

Bookmakers' profits fell by a third last year following the launch of the Lottery, although the industry had begun to recover through the introduction of fruit machines, evening racing and relaxed rules on facilities.

But Mr Paddy Bolger, finance director of Surrey Group, which runs 23 betting shops and estimates it lost more than £100,000 after Saturday, probably spoke for most bookmakers when he said: "This was a catastrophe for the betting industry."