By Keith Weir
LONDON, Jan 14 (Reuters) - Britain's bookmakers were left nursing losses totalling up to 30 million pounds ($49 million) on Tuesday after the top seven teams in English soccer's Premier League all won their latest round of matches.
"This is as bad a weekend as there's ever been," said Ladbrokes spokesman Ciaran O'Brien, while William Hill compared the impact to when jockey Frankie Dettori rode seven winners at a race meeting at Ascot in 1996.
League leaders Arsenal beat Aston Villa 2-1 on Monday night to ensure that all of the leading teams down to Manchester United in seventh place clinched victories.
Bookmakers rely on slip-ups by the favourites - who have the shortest odds but attract the most bets - to help them make money from gamblers.
Ladbrokes estimated that the cost to bookmakers was more than 20 million pounds, while rival Coral put the total bill at 30 million.
"It was another 'magnificent seven' for football customers over the weekend, with the top seven in the league all hammering the bookmakers with winning results," said William Hill spokeswoman Kate Miller.
Ladbrokes, Britain's second-largest bookmaker, will issue a trading update to investors on Thursday, while larger rival William Hill follows on Friday. Happily for them, the updates will cover the period to the end of 2013 and not include the impact of last weekend.
Shares in bookmakers have been under pressure in recent days after Prime Minister David Cameron added his voice to political concern over roulette-style "fixed odds" gambling machines in betting shops, which have grown to account for a big chunk of their retail profits.
Ladbrokes shares, which had plunged last week to a 17-month low of 161.3p, closed little changed at 165.2p, while William Hill fell 2.3 percent to 372p, not far from last week's two-month low of 367.3p.