Sir Ed Davey received a grilling from members of the public as he faced tough questions about his record in the coalition years and as minister in the Horizon scandal.
During the BBC Question Time special, the Liberal Democrat leader was challenged by a student over the abandoning of the party’s pledge to scrap tuition fees in the coalition government.
Sir Ed was also asked whether he was “proud” of his conduct as postal affairs minister under the coalition government between 2010 and 2012.
In response to the student, he said: “I understand why your generation lost faith in us. It was a difficult government to be in.”
Sir Ed said the loss of trust in his party after that period was “very scarring” and admitted he was “not proud” of some of the votes he had to take part in.
He added: “The thing I learned from that process – the whole process, fees, but other things too – was you shouldn’t promise what you can’t deliver, and I think we did in 2010.”
Asked if he is making promises he cannot commit to in the current election campaign, Sir Ed replied: “Absolutely not. It was the big lesson I learned.”
The Lib Dem leader has recently come under fire for failing to do more to help wrongly-convicted subpostmasters when he held the brief and for initially refusing to meet Alan Bates in 2010.
Sir Ed said he made “two big mistakes during that time”, including failing to meet the campaigner – although he subsequently did agree to meet Mr Bates – and not seeing through assurances given to him by the Post Office that Mr Bates’s assertions were not true.
“I’m sorry for not seeing through those lies. There were many ministers of all political parties during this 20-year period who didn’t see through those lies,” Sir Ed said.
He added that he hoped “people go to prison” over “the biggest miscarriage of justice in our country’s history”.
The BBC Question Time special also featured Prime Minister Rishi Sunak for the Tories, Sir Keir Starmer for Labour and Scotland’s First Minister John Swinney for the SNP.