LONDON -- The shares of William Hill (LSE:WMH) rallied 5% to 410 pence during early London trade this morning after revealing net revenue was 15% higher for the first quarter.

William Hill, the U.K.'s largest bookmaker, delivered an 8% improvement in operating profit from last year, boosted by such "good sporting results" as the unlikely Grand National winner, Auroras Encore.

Mobile and online revenues continue to drive the company's growth, expanding by 21% from last year, as punters rushed to download William Hill's mobile app 96,000 times during the Grand National and Cheltenham combined. With operating profits of 43 million pounds, the segment now represents 45% of the group's operating profits, 13% higher than last year.

While revenues at the company's brick-and-mortar betting shops were marginally higher on an adjusted basis, operating profits declined 3%, mostly due to a higher tax charge hiking operating costs by 5%.

Chief executive Ralph Topping commented:

It has been a successful start to 2013 in trading terms, moving forward with our strategy, expanding into Australia and taking full control of William Hill Online.

Cheltenham results were not as good for us this year but just after the quarter end, Auroras Encore made the Grand National a major success for William Hill, even beating our record win achieved on the race in 2009 when Mon Mome romped home at 100-1. Both of these big meetings proved to be significant attractions for mobile bettors.

With a market cap of 3.5 billion pounds, William Hill trades at just under 13 times expected earnings and on a prospective dividend yield of 3.2%.

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