Mr Findlay had been working on the case since December 2007. He is to be replaced by Maggie Scott QC, who until recently led the appeal by the man convicted of the Lockerbie bombing, Adelbaset Ali Mohmed al Megrahi.

It is understood the decision was made after discussions between Mr Sheridan and his solicitor, Aamer Anwar. Mr Findlay is understood to have been told the decision while on holiday in Singapore.

Mr Sheridan and his wife Gail are due to stand trial at the High Court in Glasgow in February. Both are accused of committing perjury during the MSP’s defamation case against the News of the World in 2006. Mr Sheridan is also accused of attempting to persuade another person to commit perjury.

The couple denied all charges at a pre-trial hearing in July and were granted bail. With around 180 witnesses named by the Crown, the Sheridans’ trial is expected to last around three months, making it the longest perjury trial in Scottish history.

Sources close to the case last night refused to comment on the reasons for the change in the defence team. In his defamation trial, Mr Sheridan successfully represented himself after sacking his legal team.

The News of the World had claimed that Mr Sheridan, while a list MSP for Glasgow and leader of the Scottish Socialist Party, had been unfaithful to his wife and visited a swingers’ club.

Mr Sheridan sued, insisting the claims were false.

After 23 days of evidence, the jury found in Mr Sheridan’s favour and awarded him £200,000 damages. However, within weeks the Crown Office instructed Lothian & Borders Police to investigate if any witnesses had lied.

Gail Sheridan is being represented in the perjury case by Paul McBride QC.