Sally Bercow has become the first tweeter to face a formal libel writ from Lord McAlpine and will fight the £50,000 claim.
McAlpine lodged the claim last Friday and Press Gazette understands it was the first (and only, as of Tuesday) legal challenge to be lodged at the High Court over tweets linking him to child abuse.
McAlpine issued the High Court writ just over a month after an allegedly libellous tweet was posted by Bercow.
Bercow was one of a number of tweeters who McAlpine claimed linked him to allegations of child sex abuse, following a Newsnight investigation.
Her 4 November tweet read: "Why is Lord McAlpine trending? *innocent face*". She afterwards denied that the tweet was libellous and now intends to dispute McAlpine's £50k claim.
Bercow has instructed media law firm Carter-Ruck to defend her. A spokesperson confirmed to Press Gazette that the claim had been made, and that it was for £50,000, but declined to comment further.
McAlpine’s lawyers have previously said 20 “high-profile tweeters” would be targeted.