A man has told the Tommy Sheridan perjury trial he saw the former MSP in 2002 at the swingers' club where he worked.
Tony Cumberbirch, 53, told the High Court in Glasgow that the club was for "wife swapping" and Mr Sheridan was there with other "Scottish" customers.
He also claimed to have removed Mr Sheridan's name from the register after being asked for a favour by a friend.
Mr Sheridan and his wife Gail, both 46, deny charges of perjury.
They are accused of lying during his successful defamation case against the News of the World in 2006.
The former SSP leader won £200,000 in damages after the newspaper printed allegations about his private life, claiming he was an adulterer who had visited a swingers' club.
Mr Cumberbirch told the court that Cupid's in Manchester was "a swingers' club - wife-swapping for liberated adults".
He had worked there for about 12 years - but was visiting socially on the night he claims to have seen Mr Sheridan.
He said: "I think it was a Friday night. There were three lads and two ladies. I know now one of them to be Tommy Sheridan. I didn't know at the time.
"It was Tommy Sheridan, two lads and two lasses in the club. They were drunk. They were drunken Scottish customers as far as we were concerned."
He added that he had not "played" with the group at the club.
Mr Cumberbirch also described the two women with the man he said was Mr Sheridan.
He said he thought one was Scandinavian and the other was "dark-skinned and a little bit chunky".
Two witnesses, Katrine Trolle and Anvar Khan, have previously told the trial they went to Cupid's with Mr Sheridan and a third, Gary Clark, said he had visited a club in Manchester which had pornography on television screens.
Mr Cumberbirch said he saw Mr Sheridan again later at a party in Wigan, hosted by a friend called Ian, but had gone to bed early, saying: "It wasn't our sort of party. They weren't our sort of people."
But he said he had been "as close" to Mr Sheridan at the party as he was in the courtroom.
Advocate depute Alex Prentice QC asked him how he later concluded that the man he had seen was Mr Sheridan.
Mr Cumberbirch replied: "Everything from this to Big Brother."
Mr Sheridan, who is representing himself, later cross-examined Mr Cumberbirch about the alleged visit to the club.
He asked the witness if there was any reason why he remembered that night.
Mr Cumberbirch replied: "Yes, I was asked to cross out a name because someone had signed in with their real name.
"It was just a numbers book - you could sign in as Mork and Mindy but we needed numbers."
Mr Sheridan then asked "what name" had been used and Mr Cumberbirch replied: "Yours."
The witness said he was asked by a friend called Robbie to remove the name "as a favour".
Mr Cumberbirch added: "It was a favour to Robbie, not to you. I have no interest in you whatsoever."
Mr Sheridan later claimed that the managers of Cupid's had told police that they did not recognise him as being there.
Mr Cumberbirch replied: "You are home and dry then - you are laughing."
He said he was "not prepared to tell lies" and was recalling what he "remembered".
Mr Cumberbirch also denied that he would go to a newspaper with the information he claimed to have or had ever been offered money.
Mr Sheridan later listed a number of Mr Cumberbirch's previous convictions, which included burglary and assault.
The former MSP claimed the witness was a "dishonest man".
Mr Sheridan said: "You are here to lie because you are going to benefit. You are a proven liar."
Mr Cumberbirch replied: "No, I am telling the truth."
The trial also heard from Mr Cumberbirch's wife, Louise, who also frequented and worked at Cupid's.
She said it was "a private members' club for like-minded people", adding that sex was "something you can get" there.
Mrs Cumberbirch also described seeing a group of five people - three men and two women - from Scotland in the club in 2002, but said it was "very hard to remember" what they looked like.
She also said the group had then gone to the party at "Ian's" house in Wigan.
The trial also heard from Iain Campbell, the SSP's regional organiser for Fife.
He said Katrine Trolle had told him at an SSP conference in 2006 that she had had an affair with Mr Sheridan.
He told the court: "She said, and I was quite surprised, that she had an affair with Tommy Sheridan and this had been going on during the Perth conference in 2005."
Ms Trolle previously told the trial her affair with Sheridan had ended in 2004 and she had not been at the 2005 conference.
Paul McBride QC, representing Gail Sheridan, said: "They both can't be right. That does not sit with what she told you in Glasgow. The account she gave the court about not being in Perth could not be correct."
Mr Campbell replied: "They are both not compatible".
Mr Campbell took over his SSP position from Jock Penman, who claimed at the trial on Tuesday that Mr Sheridan had not told an emergency meeting of the party's executive committee that he was the unnamed MSP the News of the World said had visited a swingers' club.
He said Mr Penman had told him the same thing.
But he added that Mr Penman had told him it was a chaotic meeting and "maybe" other members of the committee "heard something I didn't hear".
He also told the advocate depute: "He said to me on several occasions that he would be prepared to lie for Tommy Sheridan."
The SSP's national treasurer, James McVicar, also gave evidence, claiming he and the former party leader discussed the alleged sex club visit during a car journey from Edinburgh in 2006.
Mr Sheridan is said to have told him: "You are a working class boy. You find yourself in these places and it is on a plate. What do you do?"
Mr McVicar said he replied: "Well, you should not find yourself in these places."
Another witness, Charles McCarthy, a nurse and former SSP member, said he was in the Rat and Parrot bar when Mr Sheridan told him he had made "mistakes of a sexual nature" and confessed to having affairs and going to a sex club.
During cross-examination, Mr Sheridan told the witness he was part of a SSP plot against him.
Mr McCarthy replied: "You are like a suicide bomber - you want to take everyone with you." But he later retracted this comment.
Another witness, Glasgow SSP member William Young, told the court he was also at a meeting with Mr Sheridan at a Glasgow pub.
Mr Young claimed Mr Sheridan had told him friends Alan McCombes and Keith Baldassara had "betrayed his trust" after he "confided" in them.
Mr Sheridan said there would "no logic" why he would tell Mr Young such a thing and he replied: "There is not a lot of logic in a lot of things you do, Tommy."
Jack Ferguson, former organiser of the SSP youth wing, was later quizzed about a voicemail left on Mr Sheridan's phone.
The message claimed Mr Sheridan was a "dirty turncoat" and there were shouts of "hope your mum dies of cancer".
The call was said to have come from Mr Ferguson's phone, but the witness said he would "never do such a thing", which he described as "completely reprehensible".
However, he added it was "fair to say" people did not like Mr Sheridan.
It is alleged that Mr Sheridan made false statements as a witness in his defamation action against the News of the World on 21 July 2006.
He also denies another charge of attempting to persuade a witness to commit perjury shortly before the 23-day legal action got under way.
Mrs Sheridan denies making false statements on 31 July 2006, after being sworn in as a witness in the civil jury trial at the Court of Session in Edinburgh.
The trial, before Lord Bracadale, continues.