Has it got anything to do with the expenses scandal that’s threatened his position? Of course not!

Well, not officially anyway.

We’re told his decision to step down is because of a conflict of interest that’s going to occur when the Companies Act 2006 comes into force in April.

From that time, auditors general in the UK will have the power to audit public limited companies and will therefore come under the inspection regime of the Professional Oversight Board (which is part of the Financial Reporting Council).

Bourn is currently the chairman of the FRC and he’s decided to keep that position at the expense of his NAO role. Tim Burr will replace him.

The statement announcing Bourn’s big news is full of the usual puff that accompanies such an event. In it, Bourn relives the highlights of his career as comptroller and auditor general.

Those highlights include “securing comprehensive access to audit public money” as well as “developing the profile of our work so that we lead the public debate and focus attention on high profile projects such as the Olympics”. And let’s not forget “making a significant contribution to improving financial management in government”.

This all may be true but Bourn’s reputation has been forever tarnished by a phenomenal, three-year expenses bill that almost topped £400,000. Call me crazy but I don’t think that’s done much for improving financial management in the NAO.

Future comptrollers and auditor generals should not serve 20-year terms. Longevity can breed complacency, which, as Bourn has demonstrated, is a curse.

Now, any bets on the budget for his leaving do?