A former resident of a north Wales care home has apologised for making false allegations of sexual abuse against a Conservative politician.
Steve Messham said a case of mistaken identity had led to peer Lord McAlpine being linked to the historical claims.
It comes as the solicitor for Lord McAlpine, 70, threatened legal action against those who had named the peer in connection with the allegations.
Mr Messham offered "sincere and humble apologies" to the peer and his family.
In a statement on Friday evening, Mr Messham said: "After seeing a picture in the past hour of the individual concerned, this [is] not the person I identified by photograph presented to me by the police in the early 1990s, who told me the man in the photograph was Lord McAlpine."
Earlier Lord McAlpine's solicitor, Andrew Reid, said the peer had "no choice" but to take legal action over claims linking him to abuse at Bryn Estyn children's home in Wrexham.
Mr Reid said the claims were "false and seriously defamatory" to Lord McAlpine, who was Conservative Party treasurer from the late 1970s until 1990.
The solicitor was critical of the BBC's Newsnight, on which Mr Messham's claims were aired last week, although no-one was named.
The BBC said the Newsnight broadcast had voiced concerns raised by an abuse victim, in the public interest, but no public figure was named.
Mr Messham, a former resident of the Bryn Estyn home, last week told Newsnight that he had been abused by an unnamed, senior politician of the Thatcher era at the home.
He called for a new investigation claiming a report by Sir Ronald Waterhouse in 2000 had not uncovered the full scale of the abuse.
In a statement, also on Friday, Lord McAlpine said he had been subsequently named on the internet and by implication by other media over the claims and he was issuing a denial "to set the record straight".
Lord McAlpine said he wanted to "tackle these slurs and set the record straight".
He said: "I have never been to the children's home in Wrexham, nor have I ever visited any children's home, reform school or any other institution of a similar nature.
"I have never stayed in a hotel in or near Wrexham, I did not own a Rolls-Royce, have never had a 'Gold card' or 'Harrods card' and never wear aftershave, all of which have been alleged.
"I did not sexually abuse Mr Messham or any other residents of the children's home in Wrexham."
On Tuesday the Home Secretary Theresa May announced a new police inquiry into the allegations of child abuse in north Wales in the 1970s and 1980s.
Mrs May said the head of the National Crime Agency would lead the inquiry.
Separately Mrs Justice Macur will investigate the terms of the Waterhouse abuse inquiry, which began in 1996.
Lord McAlpine, who has been married three times and has three children, said there had been a "media frenzy" surrounding the child abuse allegations in Wales and "ill- or uninformed commentators" had used the internet to accuse him of something he had not done.
A BBC spokeswoman said: "Newsnight broadcast an investigation into alleged failures in a child abuse inquiry. It worked with the Bureau of Investigative Journalism to give a voice to concerns raised by an abuse victim.
"It was in the public interest to air these. We did not name any public figure for legal reasons. It is now for the inquiries announced by the home secretary to dig deeper into Mr Messham's concerns."
Newsnight is already the subject of a BBC inquiry, headed by ex-Sky News boss Nick Pollard, into why the programme dropped an investigation into sexual abuse claims against Jimmy Savile last year.
Lord McAlpine, whose grandfather founded the McAlpine construction firm, is a life peer who took the title of Baron McAlpine of West Green in Hampshire.
He became Conservative Party Treasurer in the late 1970s and held the post until 1990. He now lives in Italy.