The upmarket underwear firm lost the coveted honour after the woman who turned the company into one of the leading bra and knicker retailers in the world wrote a tell-all book about her professional life, giving details of her royal fittings.

June Kenton, 82, remained on the board of Rigby & Peller and continued to fit bras for the Queen at Buckingham Palace, even after her majority stake in the company was sold to the Belgian lingerie company Van de Velde in 2011.

But it emerged yesterday that Mrs Kenton’s long working relationship with the 91-year-old monarch ended shortly after she published her autobiography, entitled Storm in a D Cup, in March last year. Mrs Kenton, who with her husband Harold bought Rigby & Peller for £20,000 in 1982, sold a majority stake in it for £8million in 2011. 

In the book she wrote about fitting bras for a half-dressed Queen, who had first granted the firm a much-prized royal warrant in 1960 under previous owners. 

The businesswoman gave intimate details about her working relationship with other members of the Royal Family, including Princess Diana, Princess Margaret and the Queen Mother. 

Describing herself as “the UK’s leading boobologist” in one account to help promote the book, she noted that “even the grandest ladies need to be well-supported” and described giving the half-dressed monarch a first bra fitting. 

In a series of interviews, she told how the Queen Mother, who granted the firm a separate royal warrant from 1993, once confided that Princess Margaret liked to interfere with her choice of hats when her milliner arrived for fittings, but she still got her own way. 

“Shall I tell you what I do?” the Queen Mother said. “I pretend to listen to Margaret and then, once she has gone, I order what I want.” 

Mrs Kenton detailed how Diana came for bra fittings, ordered Israeli-designed swimsuits and accepted posters of models in lingerie and swimwear for her sons, William and Harry, to put up in their studies at Eton.

Yesterday Russell Tanguay, director of warrants at the Royal Warrant Holders Association, confirmed that Rigby & Peller, whose flagship store is near Harrods in Knightsbridge, had lost its warrant.

“This would have been in the middle of last year,” he said.

He explained that firms have a certain amount of time before they have to remove the royal coat of arms, earned when a company has supplied the Queen, the Duke of Edinburgh, or Prince Charles for five out of the past seven years, from their promotional material and shop signs.

And he added: “We don’t go into details.” Mrs Kenton and the company, whose other customers have included Joan Collins, and Margaret Thatcher, proved to be unusually reticent last night.

Buckingham Palace said: “In respect of royal warrants, we never comment on individual companies.”

Bras at Rigby & Peller can cost upwards of £100 and briefs nearly as much.