Betting firm William Hill saw operating profit drop by 19% in its first quarter thanks in part to a disastrous week in January, in which it lost £14m ($21m, €19.5m) on a series of turn ups for the books.

The company was also forced to pay £20m as a result of the new point of consumption tax (POCT) and more machine games duty, introduced in March 2014.

William Hill's operating profit dropped to £16m in the 13 weeks leading to 31 March.

In the third week of January, the bookmaker said that it lost £14m after a string of surprising results, including Chelsea's 5-0 thrashing of Swansea at the Welsh club's home stadium. It was the worst defeat for the Swan's since their promotion to the Premier League in 2011.

James Henderson, chief executive officer, said: "After a weak January, we saw improved wagering trends over the remainder of the quarter.

"Online wagering grew 20% in February and March and 29% for the Cheltenham festival.

"Looking forward, as the end of the football season draws closer, we have not as yet made up the shortfall arising from the £14m loss in Week three given the relatively weak first quarter sports betting margin."

William Hill shares dropped by 3.55% to 359.10 in early morning trading on the back of the results.