The Independent newspaper reports that around 1,000 original tweets have already been targeted, while 9,000 retweets – Twitter’s language for re-posted comments – are also expected to spark legal action, meaning the case could involve the largest number of defendants in British legal history.
Among those targeted are the wife of the Speaker of the House of Commons, Sally Bercow, and comedian Alan Davies, who both mentioned Lord McAlpine on their Twitter accounts.

Charity donations

Around 40 Twitter users have already contacted the peer to apologise, with reports suggesting they will be asked to pay £5 to charity. However, high profile celebrity tweeters could be treated differently.
Lord McAlpine has already agreed a settlement of £185,000 with the BBC following its broadcast of a now-discredited report into sexual abuse claims at a care home in North Wales, which prompted the tweets.
The former Tory treasurer has said he would have pursued the BBC for a higher settlement but held back as it is publicly funded. He is expected to chase a larger pay-out from commercial broadcaster ITV, after a programme presenter Philip Schofield accidentally showed a list of alleged paedophiles on camera as he passed it to UK Prime Minister David Cameron.
Lord McAlpine's solicitor Andrew Reid – who has reportedly written a 15-page letter to ITV encouraging settlement -- said the presenter had 'embarrassed the Prime Minister and destroyed the reputation of my client'.

Disciplinary action

ITV has said it is already taking disciplinary action following the incident, while the country’s broadcasting watchdog, Ofcom, has launched its own investigation into the incident, reports the BBC.
An ITV spokesman said: ‘We have received correspondence from Lord McAlpine's representatives and we will be responding in due course.’