UPDATE 2-UK sales sizzle in May sun, fan rate hike bets

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By Matt Falloon and David Clarke

LONDON, June 19 (Reuters) - An early summer heatwave sent Britain on a shopping spree in May, driving retail sales up at the sharpest pace in more than two decades, boosting expectations the Bank of England will raise interest rates.

Policymakers, so far, have signalled they are in no rush to hike rates, despite inflation fears, because the economy is expected to slow sharply as the credit crunch feeds through to households.

The BoE expects consumer spending to tail off as pay growth stalls and banks clamp down on lending, but official retail sales data on Wednesday defied all expectations -- showing a 3.5 percent leap in volumes during May.

That was the strongest since the series began in 1986 and left analysts, who had expected a slight fall, dumbstruck.

"I'm staggered," said Philip Shaw, chief economist at Investec. "The figures are on a completely different plane compared to what markets were expecting."

Official sales data has been surprisingly strong this year, puzzling policymakers and deviating from weaker evidence elsewhere.

But the longer the official numbers defy expectations, the more confident markets will grow in betting on higher interest rates.

Record sales of food and clothing, undoubtedly helped by the hottest weather for May on record, contributed most to the knockout performance -- but there was strength across the board.

Household goods sales -- an indication of how prepared Britons are to part with larger sums of cash -- rose 2.6 percent on the month.

BUMPER SUMMER

Shops did not need to slash prices anywhere near as heavily as they have had to in recent months to get consumers spending, with the measure of discounting at its tamest in nearly a year.

The average value of weekly sales was also strong, up 7 percent on a year ago to 5.3 billion pounds.

Markets reacted swiftly to price in interest rate rises in the next few months with the pound jumping nearly a full cent against the dollar. Many analysts have been expecting the BoE to cut rates later this year to shore up a slowing economy.