The BBC was forced to defend one of its top bosses tonight after he wrongly claimed that the Queen had "walked out in a huff" during fly-on-the-wall documentary, leading to a humiliating apology by the corporation to the Royal Family.

Peter Fincham, the BBC One chief controller, yesterday presented the media with a promotional trailer of the station's forthcoming documentary A Year With A Queen, in which he said that the Queen had walked out of the room during an on-camera argument with the portrait photographer Annie Leibovitz at Buckingham Palace.

After Ms Leibovitz told the Queen to remove her crown during a photoshoot, Mr Finch told reporters that the Monarch walked out. "Annie Leibovitz gets it slightly wrong and the Queen walks out in a huff," he said, during a media briefing publicising the corporation's autumn coverage.

However today, the BBC Trust was forced into a humiliating apology to the Queen and Ms Leibovitz, admitting that its promotional trailer for the programme had been edited in the wrong order and had been aired by mistake.

As a result, the scene which purported to show the Queen storming out of the room was, in fact, a shot of her walking into the photoshoot - and that the alleged walkout never happened.

After initially apologising at lunchtime today, the BBC tonight issued a fresh statement trying to explain what it said was a miscommunication.

"The extracts shown from A Year with the Queen were supplied by RDF (the documentary's production company), who had made an early assembly of the footage several months ago," a BBC spokeswoman said.

"This assembly was never intended to be seen by the public or the press. Unfortunately, this assembly was given in error to the BBC personnel who were preparing the BBC One autumn launch tape.

"RDF did not have an opportunity to review the BBC One launch tape, but would like to apologise to the Queen and Annie Leibovitz for this error."

A spokeswoman defended the comments made at yesterday's launch by Mr Fincham, which led to widespread media coverage of a misleading story, saying that they were made in entirely good faith because he had viewed the promotional trailer which showed what he thought was the Queen walking out. "Peter had no idea that it might have been done wrongly," she said.

She added, of the new statement issued tonight: "We're not taking our initial apology back. We just want to explain things a little better."

During a day of embarrassing internal wrangling, the BBC Trust, the body that oversees the corporation, said it would demand that Mark Thompson, the corporation's Director-General, explain the situation when he talks to next week's Trust meeting.

"The BBC Trust has requested the Director-General to give an account at next week's trust meeting of the events which led to the BBC issuing an apology about the trailing of a documentary about HM The Queen," a statement said.

In the full footage of the photoshoot - which was undertaken shortly before the Queen's 80th birthday and a trip to the US - the Queen is seen walking into a room in Buckingham Palace cluttered with camera equipment wearing her crown and Order of the Garter robes.

Ms Leibovitz tells her: "I think it will look better without the crown because the garter robe is so..."

But before the photographer can finish saying "extraordinary", the Queen gives her an icy stare and replies: "Less dressy? What do you think this is?" The trailer then cut to the misplaced image of the Queen apparently storming off, saying to her lady-in-waiting: "I'm not changing anything. I've done enough dressing like this, thank you very much."

Today's admission will cause embarrassment to the corporation, as its trailer was given widespread coverage on television and on websites yesterday, and in newspapers today.

The five-part series tracking the Queen was billed as the highlight of BBC One’s autumn season. It captures the working life of the Royal Family, with snippets unveiled today showing the Duke of Edinburgh, the Prince of Wales and Princes William and Harry on duty.

Ms Leibovitz is one of the world’s most famous photographers. Her work regularly appears in Rolling Stone and Vanity Fair magazines.

She is renowned for making unusual requests of her subject having once dunked Kate Winslet in a tank of water, and snapped Clint Eastwood after he had been tied up with ropes.

Buckingham Palace said it would not be issuing a comment about the BBC's apology.

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