In a television interview to be broadcast tonight, the Prime Minister will concede 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.
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."
Mr Brown was also pressed in the pre-recorded interview about recent allegations he had bullied staff in Downing Street.
Asked if he understood people could find him intimidating, he said: "I don't think intimidating … I think it's difficult for people. You know, I go out to meetings and to events in the country all the time … I hope I am not intimidating, I hope I am the opposite, I hope I am willing to listen and willing to learn. And then I'll go back and I'll make up my mind and say, 'This is what we now do'."
On presentational politics, he admitted his wife Sarah would like to see him better dressed, and added: "I'm not so good at that."
Asked if he could use "some of Tony Blair's polish", he replied: "Tony was great, but I don't claim that I am some alternative.
Meanwhile, Mr Brown stirred a fresh row over legal aid for the three former Labour MPs accused of fiddling their expenses.
The Prime Minister declared that David Chaytor, Elliot Morley and Jim Devine would have to refund their legal expenses, prompting a clash with the Law Society, which represents solicitors in England and Wales.
Labour has introduced reforms to enable the courts to means-test white-collar defendants for legal aid, but the changes are not being implemented in time to cover the ex-MPs' case.
However, Mr Brown told the BBC: "I think this money will have to be paid back by these politicians. I think the evidence is that people in their position will have to pay back the money – or most of the money – they get in legal aid.
"We have actually abolished this free legal aid from the end of June, so it has to be means-tested from the end of June, and they wouldn't have got it in these circumstances. The law has changed, so I think the money will have to be paid back."
However Desmond Hudson, chief executive of the Law Society, said: "It is a principle of our legal system that anyone charged with a criminal offence before the Crown Court is entitled to legal representation.
"This is a vital part of ensuring that charges against a defendant must be fully proved in a fair trial. This must require the provision of legal aid. The government has recently introduced a means test for such cases to ensure that those who can afford to contribute to the costs of their representation are asked to do so. Depending on the wealth of the individual and the cost of the case, their contribution could cover all costs."