Alistair Darling’s offer of immunity from prosecution to those providing evidence against market manipulators and destabilisers of the financial system follows complaints by the Financial Services Authority, the UK regulator, about “unfounded rumours ... sometimes accompanied by short-selling”.

If this threatened use of anti-racketeering legislation by the British chancellor of the exchequer brings to mind an episode of The Sopranos, there is more than a passing resemblance to the American television drama. In its second series, the New Jersey crime family diversifies into a stockbroking venture, in which the salesmen try to “pump and dump” worthless stocks by cold-calling gullible investors.