It would appear to be a marriage made in heaven. On one side there are the banks, which – in the wake of the credit crisis – are desperate to secure ready access to liquidity. On the other side are pension schemes, which hold plenty of liquid securities on which they are earning meagre returns because interest rates are so low.

The idea of pension savings being used to fund investment banking deals and corporate transactions may raise eyebrows in some corners. But so-called "collateral upgrade transactions" - whereby schemes lend government bonds to banks for a fixed period - allow pension funds worried about their long-term solvency to put money away for a rainy day by boosting returns from their assets.