Construction boss Cullum McAlpine wriggled and writhed today when MPs grilled him about grand-scale blacklisting.
Flanked by the Sir Robert McAlpine company's head lawyer, he repeatedly uttered the words "I don't know," "I can't say" or "I can't answer that question."
MPs on the Scottish affairs select committee became more and more frustrated as they tried to squeeze admissions out of Mr McAlpine over his company's close links with the Consulting Association (CA).
The CA was disbanded in 2009 amid a major scandal over thousands of blacklisted workers.
Mr McAlpine, a director of the construction company and former chairman of the CA, admitted that he had chaired twice-yearly meetings of the notorious organisation.
But when sceptical MPs asked for more details he replied: "I don't remember very well" and "my memory is pretty rusty."
Dundee Labour MP Jim McGovern bluntly accused Mr McAlpine of "hiding behind" recently deceased former CA blacklister Ian Kerr, "who can't answer."
Labour MP Pamela Nash challenged Mr McAlpine about his claim that the McAlpine company had never operated a blacklist.
"Are you saying that the CA list was not a blacklist?" she asked.
"I'm afraid I cannot answer that question," he retorted.
Trying another tack, Ms Nash asked: "Has your company ever asked anyone else to operate a blacklist?"
"No" came the answer.
Laughter broke out in the room as committee chairman Ian Davidson MP intervened and asked: "Can I just clarify just what you thought that the Consulting Association was doing then?"
Grudgingly, Mr McAlpine offered his view that a blacklist was a list of names which "automatically" prevented those on the list from enjoying the benefits of a club or a job.
He admitted that his construction company had used the CA "a lot" during 2008, when it was extremely busy with Olympic projects, defence ministry work and shopping centres.
The Home Office carried out vetting of everyone who worked on the Olympic site, he added.
The McAlpine company had paid legal costs incurred by Mr Kerr upon his prosecution in 2009 for administering the CA database.
When asked if he knew that the McAlpine company sent cheques for £15,000 and £8,000 to Mr Kerr's daughters to cover their father's fines and legal fees, Mr McAlpine replied: "I did not know that at the time."
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