Bank of England governor Mark Carney said the "age of irresponsibility" in the City is over as regulators make financial markets fairer and hold "bad apples" to account.
Mr Carney said the Bank and authorities were bringing the era of "heads-I-win, tails-you-lose capitalism" to a close to ensure bankers will be punished for wrongdoing and that markets are resilient and "don't collapse when the going gets tough".
The governor is holding an "open forum" with policymakers, academics and senior bankers in central London to discuss the future of regulation.
He told Sky News ahead of the forum there were still "bad apples" in the industry, but said the finance sector is increasingly "part of the solution rather than the problem".
Mr Carney said Britain's financial sector had the potential to be worth six to nearly 15 times the value of the UK entire gross domestic product (GDP) by 2050.
He added that reforms of the sector and regulation were essential to keep the UK as a leading international financial sector.
He said the 2008 financial crisis and its aftermath "laid bare that many of our markets didn't live up" to standards expected of the sector.
Mr Carney told the forum that "a huge amount has already been completed to make markets fairer, more resilient, accountable and effective".
He added: "But the journey isn't finished."
Authorities must "have the courage to listen, the honesty to admit our mistakes and the confidence to set them right", according to Mr Carney.
He said: "Today is a chance to take stock and reflect - not just on our achievements but on what we might have missed, overdone, or simply got wrong.
"Because we're determined not to repeat the cycles of the past."
In a first for the Bank, it is throwing open the whole issue of financial market regulation to the public for their ideas on how to take it forward.
Around 400 people are attending the forum at The Guildhall in London, with around half securing their places through a public ballot.
But Mr Carney said the places were four times oversubscribed.
Many more are watching the event broadcast live online, including some of the 5,000 pupils from 300 schools across the UK who watched a webinar from the Bank earlier this week.
Chancellor George Osborne, who also addressed the forum, said past regulation of the City and financial sector was not good enough.
He said: "For too long we have had a situation where benchmarks were rigged. Benchmarks used by millions, to exchange money when they went on holiday. It now turns out insiders were rigging the benchmark.
"Regulators who said they knew what was going on, but of course did not," he added.
"Hopefully whoever is doing my job when next big failure happens will have many more options than I have."
He told the forum that systems to rescue banks and stabilise markets were inadequate in the past, leaving former chancellor Alistair Darling with "little option but to bail out the banks" when the crisis struck.