Mervyn King, the Bank of England governor, on Monday implicitly asserted copyright over the Treasury-bills-for-mortgage-backed-securities scheme. At a press conference he revealed that he had personally tapped out the guts of the scheme on his home computer about a week before Easter.

The Bank, he made clear, had decided in March that action must be taken. Rumours that HBOS was on the brink of collapse and the Bear Stearns crisis underlined that any bank, whether solvent or not, could fall victim to a wholesale run and the refusal by others to lend it money.