A TV production company has admitted it was to blame for a documentary trailer that made the Queen look like she had stormed out of a photo shoot.
RDF Media made the documentary for BBC One
RDF Media, which made A Year With The Queen for BBC One, said it was "guilty of a serious error of judgement".
The company produced a clip that was shown to journalists and BBC One controller Peter Fincham said it showed the monarch "walking out in a huff".
But RDF chief executive David Frank accepted it was edited out of sequence.
Mr Frank sent an e-mail to BBC director general Mark Thompson on Monday.
"I deeply regret the embarrassment this has led to for both the BBC and the Queen and wanted to apologise to you unreservedly," he said.
There was "no attempt to include anything misleading in the documentary", he wrote.
"I nonetheless condemn what was done by RDF employees in manipulating the chronology of any footage regardless of its objective, use or context.
"It has been an extremely painful lesson for those involved. I am taking steps to put in place measures which I hope will ensure nothing of this sort happens again."
He added he hoped the BBC's trust in RDF could be rebuilt but "I realise we've got a lot to make up".
Mr Thompson is due to explain the matter to the BBC Trust, which oversees the corporation and represents licence fee payers, on Wednesday.
He responded to Mr Frank by saying: "I appreciate your acknowledgement of RDF's role in this very regrettable episode and your unreserved apology."
The trailer was shown during the press launch for BBC One's autumn season last week.
In it, photographer Annie Leibovitz was seen telling the Queen she would look better without her tiara because "the Garter robe is so..."
Before she could say anything else, the Queen replied, pointing to what she was wearing: "Less dressy. What do you think this is?"
The clip then cut to the Queen walking through Buckingham Palace, saying to her lady-in-waiting "I'm not changing anything. I've had enough dressing like this, thank you very much", implying she had stormed off from the portrait session.
But in fact, that clip was filmed before the exchange over the tiara.