Gordon Brown has accepted that it was a mistake not to have taken a tougher line with the banks when he was Chancellor.
In a television interview, he said that the banks should have been more tightly regulated in the years before the financial crash.
Asked on ITV1's Tonight: Spotlight on the Leaders programme about mistakes he had made, he initially offered his decision to scrap the 10p rate of tax - something he has admitted in the past.
But pressed for a further example, he replied: "In the 1990s, the banks. They all came to us and said, 'Look, we don't want to be regulated, we want to be free of regulation'.
"All the complaints I was getting from people was, 'Look you're regulating them too much'. And actually the truth is that globally and nationally we should have been regulating them more. So I've learnt from that. So you don't listen to the industry when they say, 'This is good for us'. You've got to talk about the whole public interest."
In an interview which covered a lot of personal ground, Mr Brown disclosed that he had never overcome his shyness and admitted that he was in a "strange" profession for someone with such an attribute.
The Prime Minister stressed his "ordinary" upbringing and talked of his determination to succeed in life which had seen him never give up.
He said that he came from a background "where we've had to fight for everything we've got" and stressed that he was the leader who could make tough decisions. He understood the needs of ordinary people and had seen the blight of unemployment as a youth growing up in Kirkcaldy, Scotland, he said. His whole political philosophy was about being on the side of people.
Shadow chancellor George Osborne said: "So finally Gordon Brown admits he failed to regulate the bankers and increased taxes on the poor. His next huge mistake would be his jobs tax that will kill the recovery.
"We've had 13 years of his economic mistakes. Britain can't afford five years more."