Alistair Darling, chancellor, is to warn the City to expect further regulation and a crackdown on sloppy boardroom practices, amid fears in the Treasury that some bankers are forgetting the lessons of the financial crash.

In the chancellor’s annual Mansion House speech on Wednesday, Mr Darling aims a warning shot at those in the City, including the British Bankers’ Association, who are speaking out against new regulation forcing higher liquidity and capital standards at banks.