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* Avast hits record high

* Hiscox falls after results

* BoE to raise interest rates by 50 bps on Thursday

* FTSE 100 rises 0.5%, FTSE 250 up 0.7%

Aug 3 (Reuters) - Britain's main stock indexes closed higher on Wednesday as Avast surged after it won regulatory approval for NortonLifeLock's $8.6 billion deal, while banks rose a day before an expected interest rate hike from the Bank of England.

Shares of Avast Plc soared 43.8% to an all-time high after Britain's competition regulator said it has provisionally cleared cybersecurity firm NortonLifeLock's $8.6 billion purchase of its rival.

The blue-chip FTSE 100 index was 0.5% higher, while the domestically focussed midcap index gained 0.7%. Both the indexes clocked strong gains in July, with the FTSE 100 outperforming its global peers so far this year.

"The UK market is a defensive market, so it will tend to outperform in a year like 2022 when there are a lot of uncertainties," said Thomas Moore, senior investment director at abrdn.

"People will still pay for their energy, heating bills; they will buy cigarettes, a bottle of whiskey. Inflation and interest rates could be a problem for the UK economy, but it is unlikely to be a problem for UK stock market."

All eyes are on the Bank of England's meeting on Thursday where policymakers are expected to raise interest rates by 50 basis points after other central banks pushed up borrowing costs sharply in recent weeks, despite the risk of an economic slowdown or a recession.

UK banks rose 1.5% ahead of the decision.

"If we get the 50 basis point hike, the big winners of that will be the banking sector," said Stuart Cole, head macro economist at Equiti Capital.

"But it is going to come at the same time as consumers are facing higher cost of living with things such as inflation."

Markets also took comfort in U.S. House Speaker Nancy Pelosi's leaving Taiwan following a visit which angered China.

Hiscox dipped 0.7% after the Lloyd's of London insurer posted a first-half pretax loss of $107 million.

Homebuilder Taylor Wimpey Plc gained 5.5% after it forecast annual operating profit near the top end of market consensus range. (Reporting by Sruthi Shankar, Shreyashi Sanyal and Johann M. Cherian in Bengaluru; Editing by Sherry Jacob-Phillips, Shailesh Kuber and Angus MacSwan)