Accelerated Trackers are listed on the London stock market and are dealt just like ordinary shares through a stockbroker, although with the advantage that no stamp duty is payable when buying.

Even if all the tax they pay is VAT on expensive meals in London restaurants or stamp duty on flats in Mayfair, it is still additional income for Mr Brown.

If he had purchased an apartment of the same value, he would have had to put down 30%, pay a large stamp duty and attorney fees.