Four former UBS chiefs were grilled by MPs on Thursday over their knowledge of the manipulation of the London interbank offered rate setting.
Ex-group chief executive Marcel Rohner and former head of UBS's investment arm Huw Jenkins were among the representatives called before the commission to give evidence over failings at the Swiss bank which resulted in Libor being manipulated for years.
Libor is used as a benchmark for pricing trillions of dollars of loans. Even small inaccuracies in the rate affect investment returns and borrowing costs.
UBS was fined a record $1.5 billion (£931.8 million) in December for manipulating Libor interest rates. Swiss national Dr Rohner said he was "shocked" and "ashamed" about the affair, but he and his colleagues denied knowing anything about the rigging of interest rates until they read reports in the press.
"The times I was leading this institution were so extreme I was fighting permanently for survival," Rohner said, adding: "I did the best I could."
Commission chair and conservative MP Andrew Tyrie was clearly unimpressed with the responses; he stated: "The level of ignorance in this board seems to be staggering to the point of incredulity."
The spirited attacks kept coming; Lord John McFall, well known to banking commentators from his time as chair of the Treasury Select Committee following the financial crisis, landed the most comedic blows, accusing the UBS four of being like Captain Renault, the police captain in the classic Humphrey Bogart film, Casablanca.
In the film Captain Renault threatens to close down Rick's (Humphrey Bogart's) nightclub and gambling venue, saying: “I'm shocked, shocked to find that gambling is going on in here!”, despite placing bets himself on occasion.
Dutifully, a croupier appears with his winnings, for which Renault thanks him before walking out.
McFall said: "I would suggest you knew that gambling was going on and you went out the door with much more winnings than Captain Renault."
Thee four former board members of UBS denied the suggestion.
Jerker Johansson, who headed the investment bank for just over a year from 2008, also came under fire after admitting the management had been negligent not to detect the misconduct, adding the manipulation was tantamount to stealing.
The two-tier board structure in place at many European banks, including UBS, did not work well during crises, he told the MPs.
"It was dysfunctional. It means the supervisory board has all the responsibility but cannot act operationally ... that made the decision making a complete nightmare."
Tyrie closed the session by telling the quartet: "We've heard of appalling mistakes that can only be described as gross negligence and incompetence... You were ignorant and out of your depth."
The Parliamentary Commission on Banking Standards, a cross-party panel of MPs and Lords, is expected to make recommendations on reforming the banking sector to government and the industry before the end of March.