Tommy Sheridan, the former leader of the Scottish Socialist party and MSP, has been found guilty of lying under oath when he won a £200,000 libel case against the News of the World.

The 46-year-old politician, who was a member of the Scottish parliament for eight years, was convicted of committing perjury when he convinced a libel jury in August 2006 that the Sunday tabloid had lied about his adultery and visits to a Manchester sex club. He was told he can expect to go to jail.

After a trial at Glasgow high court lasting more than 11 weeks, the jury of 12 women and two men took over a day to reach a majority verdict. .He was convicted on five of six elements of the perjury charge.

The judge, Lord Bracadale, told Sheridan: "You have been convicted of the serious offence of perjury and must return on January 26 expecting to begin a prison sentence."

The verdict was met with silence despite the large numbers of Sheridan family and supporters. Afterwards a statement was read on Sheridan's behalf by his solicitor Aamer Anwar. "I make no apology for taking on the might of Rupert Murdoch," it read.

His wife, Gail then made a statement of support and thanked the couple's friends. "I have and will always stand by Tommy," she said. The pair then embraced.

After originally facing 18 separate allegations of perjury contained in two different charges, the prosecutor, Alex Prentice QC, abandoned 12 allegations to "focus" the case for the jury.

He remained accused of lying on oath at the libel case about a Scottish Socialist party meeting where he admitted having an extramarital affair with the former NoW columnist Anvar Khan and visiting the sex club, and of lying about another affair with a former SSP activist, Katrine Trolle.

The jury found him guilty on five of the allegations, but found him not guilty with relation to the allegation concerning Khan.

Last week Sheridan's wife Gail, also 46, was cleared of also committing perjury at the 2006 libel trial after the prosecution decided the case against her was too weak and insubstantial.

The trial, which began on 4 October, has already made legal history as the longest perjury trial in Scotland, hearing more than 60 witnesses. There were several delays after Sheridan sacked his barrister Maggie Scott QC and represented himself in court. He continued to get legal advice from Anwar whose costs had to be paid by the Scottish Court Service.

It is estimated to have cost up to £4m: Lothian and Borders police, which deployed more than 20 detectives and spent 52,000 hours on the case, said its costs had hit £1.4m when the Sheridans were charged in 2008.

Before the jury was sent out to consider its verdict yesterday, Sheridan appeared to have reduced several jurors to tears after claiming they were the only people he was scared of.

During his four-and-a-half hour summing up speech, he said he was not scared of anyone else: not the NoW nor the police, who raided his home and scared his daughter, and pursued a "vendetta" against him.

But in a moment which capped all the drama which this case has seen, he paused, to hold back tears with a choking note on his voice. "I'm frightened of you. I'm frightened of you because you can do something that the NoW will never be able to do. You can separate me from my wife. You can make me break a promise to my daughter that I would spend Christmas with her," he said.

He broke down again as he spoke. There was a cry of "come on Tommy" from the packed court room.

Lord Bracadale ordered the jury to discard Sheridan's emotional appeals and all his references to his daughter, and not to consider any of the consequences of their verdict. He urged the jury to be dispassionate and focus on the facts.

He said: "This is not a political court, you do not judge people on their politics," adding: "It is not your function to judge the sexual morality of anyone involved in this case."

In his closing speech to the jury on Monday, prosecutor Alex Prentice said the charge of perjury was extremely serious. Sheridan was not accused of murder or rape, but deliberately lying on oath was still a crime.

Perjury "is a serious crime for the simple reason that our whole system of justice falls apart if perjury is acceptable behaviour", he said. "It is not acceptable and should never be acceptable in a mature and dignified democracy. If we let perjury pass without action, we let ourselves down."

Sheridan still faces at least one further case: the NoW has an outstanding appeal against the libel jury's verdict in 2006 and is expected to quickly reopen its legal action.

But Sheridan has indicated he could yet sue the NoW and its parent company News International after the discovery that the convicted phone hacker Glenn Mulcaire, who worked exclusively for the NoW, had Sheridan's private mobile details in 2004.