A TV production company has publicly admitted that it is to blame for the blunder concerning a documentary trailer which falsely appeared to show the Queen storming out of a photo shoot.
The acknowledgement from RDF Media that actions by its staff had caused "embarrassment" to both the Queen and the BBC comes as the broadcasting corporation prepares to explain to independent trustees how the gaffe occurred.
BBC director general Mark Thompson is to appear before the BBC Trust tomorrow to give a full account of the matter to the body which represents licence fee payers.
In an e-mail sent to the BBC chief yesterday, RDF chief executive David Frank admitted that his company was "guilty of a serious error of judgement" over the footage it provided.
BBC bosses were left red-faced last week after they released the clip, which implied that the Queen had stormed out of a photo shoot after a disagreement with US photographer Annie Leibovitz.
The clip was part of the forthcoming documentary, A Year With The Queen, which RDF made for BBC1.
Aired during the press launch for the channel's autumn season, the trailer showed the monarch disagreeing with the celebrity snapper over the removal of a tiara.
She was subsequently shown making what appeared to be a hasty exit, complaining: "I'm not changing anything."
However it subsequently emerged that the clips had been edited together in the wrong order and that the Queen was in fact arriving for the photo shoot in the offending section.
Expressing his regret over the incident, Mr Frank said: "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."