"They are selling the family silver on the cheap," said John Hanson, who represents a family trust holding 10 per cent of Park Lane, and who claims to speak for small shareholders with an additional 4 per cent of the company.
Mr Hanson claimed the company had rejected offers of up to pounds 113m for the hotel in recent years, and said a more realistic value would be around pounds 70-80m.
"This is a luxury hotel, and should fetch a better price," Mr Hanson said. "The current management are just cutting and running."
Shareholders representing 72 per cent of the company have given their irrevocable support to the offer, according to a statement by ITT Sheraton.
The Park Lane was built in the 1920s by a group of Yorkshire families, whose descendants continue to own it. It was previously listed on the 4.2 market, which was wound up last year.
The offer equates to about pounds 145,000 a room for the 311-room hotel. The Ritz was recently sold for about pounds 575,000 a room.
As part of its unsuccessful defence against a pounds 3.8bn bid by Granada, the media and leisure company, hotels group Forte issued a revised valuation suggesting an average of about pounds 285,000 a room.
There was speculation yesterday that ITT Sheraton planned to convert the hotel, in the Mayfair district of London, into a casino, in light of the Government's planned relaxation of gaming laws.
Last month, the US company bought the Sheraton Skyline hotel at Heathrow Airport, which it had been managing.
Daniel Weadock, ITT Sheraton's chief executive, said in a statement: "This strategic blend of acquiring premier hotels in key markets, opening new hotels in markets where it is advantageous, and broadening our base of managed hotels demonstrates our goal to expand our base of leadership in gateway cities."
The sale, even at pounds 45m, encouraged analysts that the hotel market may not as affected as feared by the resumption of bombing by the IRA. They said the sale was a boost to Granada, which is aiming to sell as much as pounds 2bn of assets to pay down debt following the takeover of Granada.
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