Lord McAlpine is understood to have agreed a £185,000 payout from the BBC after an episode of Newsnight led to him being branded a paedophile.
The settlement is just the first of a series of damages settlements sought by the Tory grandee's lawyers, who warned yesterday that they are after Twitter users who wrongly identified him as a child molester.
Among his first Twitter target is Sally Bercow, the wife of the House of Commons Speaker, who as internet rumours spread of who might be the senior Tory linked to child abuse in North Wales care homes, could not resist tweeting: "Why is Lord McAlpine trending? *innocent face*"
She later apologised in an abject tweet, but her name is on a list drawn up by lawyers acting for Lord McAlpine as one of the Twitter users who face being sued. Andrew Reid, acting for the former Tory treasurer, also made the unorthodox move of proposing that the perpetrators of the tweets come forward to agree a settlement – or face being sued. He added: "Very sadly, we are going to have to take action against a lot of people."
The payout from the BBC was negotiated as Lord McAlpine gave an interview to Radio 4 in which he spoke of how being falsely accused of paedophilia "gets into your bones" and "rots your life".
"There is nothing as bad as this that you can do to people," he said. "Because they [paedophiles] are quite rightly figures of public hatred. And suddenly to find yourself a figure of public hatred, unjustifiably, is terrifying.
"It can't be repaired. It can be repaired to a point. But there is a British proverb which is insidious and awful where people say: 'There's no smoke without fire'... It's very difficult and so this is the legacy that sadly the BBC have left me with."
He expressed sympathy for Steven Messham, the abuse victim who issued a public retraction and apology once he realised that he had mistakenly identified Lord McAlpine as his abuser.
"I was very grateful that he said this. I actually have deep sympathy with him. He's obviously a man who has suffered a lot in his life. I've been blessed in my life. I've been very lucky. But he's had a terrible time. But it wasn't me."
One Twitter user linking Lord McAlpine to the story was George Monbiot, a Guardian columnist. He wrote saying he felt "worse about this than anything else I have ever done".