The Bank of England and the government covered up the failure of a World War One war loan bond to avoid damaging national morale, it has emerged.
The government wanted to use the loan to raise £350m to fund the war, and articles in the Financial Times claimed it had been oversubscribed.
However, the loan raised less a third of its target and the Bank of England was asked to help find the rest.
Current Bank employees discovered what had happened from old bank ledgers.
Investors could have made 4.1% by putting in some money, well above the 2.5% which was payable on other government debt at the time, but the bond still only managed to attract a narrow pool of investors.
Fewer than 100,000 people invested, with half of them putting in £200 or less, the Bank Underground blog reveals.
The Bank of England bought up the remaining securities in the name of its chief cashier, so as not to arouse suspicion.
And as the war dragged on, the Bank had to use its own reserves to provide money for the war effort on several other occasions.