UPDATE 2-William Hill backs a winner with in-play betting

* H1 operating profit 147.7 mln stg vs f'cst 141.6 mln

* In-play betting stakes double

* CEO says trading resilient in tough environment

* Says looking to make further acquisitions

* Shares down 0.1 pct, outperforming wider market (Adds CEO, analyst comment, shares)

By Matt Scuffham

LONDON, Aug 4 (Reuters) - Britain's biggest operator of high street betting shops, William Hill , beat market expectations with a 9 percent rise in first-half operating profit due to a surge in the popularity of in-play gambling.

The only bookmaker to offer point-by-point betting on tennis at the Wimbledon Championships, said the amount of bets staked in-play had nearly doubled during the period and now accounted for more than 40 percent of overall sports betting.

William Hill, which has some 2,350 betting shops and takes more than a million bets a day, said operating profit for the half year to June 28 rose to 147.7 million pounds ($241.1 million).

That was ahead of the consensus forecast of 141.6 million, according to a company-supplied poll of 18 analysts.

"This is an especially strong set of results for William Hill in challenging economic conditions," Chief Executive Ralph Topping said on Friday.

William Hill said revenue rose by 7 percent to 567.8 million pounds, incorporating 23 percent online growth and 2 percent growth in retail.

The company said trading in the last five weeks was in line with its expectations, with net revenue down 2 percent against the tough comparative of last year's soccer World Cup.

"I think we have been very resilient. It is rough for the consumer out there but what we are seeing is the consumer perhaps abandoning large buys. Leisure spend seems to be escaping any restraint," Topping said.

Shares in William Hill, which have risen by more than 40 percent since last November, were down 0.1 percent to 217.9 pence at 1100 GMT, outperforming the broader mid-cap market which was down 3 percent .

Peel Hunt upgraded its forecast for William Hill's full-year operating profit by 4 percent to 270 million pounds.

"This was an excellent first-half performance from all areas of the business," said Peel Hunt analyst Nick Batram.

William Hill acquired three U.S. businesses in the past six months and is still looking to expand internationally.

"We're having lots of discussions with lots of people. Anything we do will be in the regulated markets. There's other interesting territories around the world that we would look at, but the art is in the delivery," Topping said.

Rival Ladbrokes reported a 6 percent decline in first-half operating profit on Thursday.

($1 = 0.613 British Pounds)

(Editing by David Hulmes) (Reporting by Matt Scuffham, Editing by Rosalba O'Brien)