Lord McAlpine is set for a high court battle with Sally Bercow after she refused to back down in the face of a legal challenge from the former Tory peer over an allegedly libellous tweet.
McAlpine demanded £50,000 libel damages and an apology from Bercow after her Twitter post which he claimed linked him with allegations of child sex abuse.
Now the Commons Speaker's wife has instructed the media law firm Carter-Ruck to defend her after McAlpine filed a formal libel claim at the high court in London.
Lawyers for the ex-Tory party treasurer filed a formal libel claim on 7 December after weeks of attempting to settle with Bercow out of court.
Bercow has consistently denied that her tweet on 4 November – "Why is Lord McAlpine trending? *innocent face*" – was defamatory.
But the formal filing of McAlpine's libel claim is the first sign that the dispute could result in a trial at the high court.
Bercow tweeted to her 56,000 followers: "Final on McAlpine: am VERY sorry for inadvertently fanning flames. But I tweet as me, forgetting that to some of u I am Mrs bloody Speaker." She temporarily deleted her Twitter account after the uproar.
Lawyers for McAlpine have previously said he would target 20 "high-profile tweeters" over the defamatory allegations, which were made on various social networks following a Newsnight report that incorrectly linked the ex-Tory party treasurer with child sex claims.
The BBC and ITV have agreed to pay McAlpine damages of £185,000 and £125,000 plus legal costs, respectively.
Bercow declined to comment. McAlpine's lawyer had not responded to a request for comment at the time of publication.
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