Publishing sources confirmed that the author, regarded as a serious biographer and a "safe pair of hands", had unwittingly included potentially sensational disclosures about the Royal Family in her first draft and had to submit it to important cuts.
A spokeswoman for the publishers, William Heinemann, said: "It was checked for libel. It was seen by a libel reporter and our own in-house solicitor."
The Times, which is publishing extracts from Sarah Bradford's biography, left out some of the more explosive revelations through fear of offending some of its traditionalist readers. In particular, yesterday's extract did not name a former lady- in-waiting dismissed by the Queen, allegedly for warning her of rumours about Prince Philip's infidelity.
Some years later the lady-in-waiting committed suicide. The Daily Mirror yesterday named her as Lady Alice Egerton, who died in 1977, aged 52.
The Times also decided not to run a news story on the claims, on the grounds that people would still buy the paper to read the extract, especially at its reduced price of 20p, but it was not worth the risk of provoking royalist readers into cancelling their orders.
Even in its expurgated form, the biography set off yet another round of speculation about the private lives of the Royal Family. The publicity took Buckingham Palace by surprise, as hints that the Duke of Edinburgh had been unfaithful came from an apparently impeccable source. Sarah Bradford, Viscountess Bangor, has quoted from what she describes as "private diaries", "a private, unpublished memoir" and "private conversations". Her earlier biography of George VI was well received by the Queen.
Buckingham Palace has dismissed the biography as "tired, recycled speculation".
Elizabeth, A Biography of Her Majesty The Queen examines rumours that swirled around the earlier years of the royal marriage which suggested that the Duke was unfaithful, and his reputation for having a roving eye.
Gossip surfaced as long ago as 1948, when Philip was a member of the Thursday Club, an informal group that met once a week for lunch in a room above Wheeler's restaurant. The club was started by society photographer Baron, and it was not long before gossip columnists linked his then girlfriend, Pat Kirkwood, a beautiful musical star, to Philip.
One of the few surviving members of the club is the veteran harmonica maestro Larry Adler. Yesterday he said: "The Thursday Club was the most wonderful creation. It was all male and completely informal. I never referred to Prince Philip in any terms other than plain Philip.
"We were very frank with one another but never discussed our sex lives. We knew of the gossip about Philip, but it didn't appear to affect him and we never dwelt on it."
Last night the Duke of Sutherland denied the claim that Lady Alice Egerton - his sister - was asked to leave Buckingham Palace because she tried to warn the Queen about the Duke of Edinburgh's flirtations. He broke a 20-year silence to describe the book as a "slur" on the Queen, and said his sister left "because she had a mental breakdown - as simple as that".
In 1992, Prince Philip gave a rare interview to the Independent on Sunday in which he laughed off rumours of infidelity, and said: "For the last 40 years, I have never moved anywhere without a policeman accompanying me. So how the hell could I get away with anything like that?" The next day the journalist received a letter from Buckingham Palace warning her that she could face legal action if she pursued this line of inquiry.