The public had been completely in the dark about Mr Wallis's temporary employment as a consultant until his arrest last week by detectives from Operation Weeting, the phone-hacking investigation.

BBC: Analysis: Met police resignations

Mr Obama has let one former tax-avoider through: Tim Geithner, the new treasury secretary, who failed to pay self-employment taxes when he was a consultant for the International Monetary Fund. (Foes of America's absurdly complicated tax code were delighted to note that even a reputedly brilliant economic mind failed to comply with it.) But with the financial and economic crisis raging, Mr Geithner appeared simply too important to lose.

ECONOMIST: Tom Daschle: The importance of being sinless | The

The consultant may favor the manager purely because of the prior employment relationship.

FORBES: A Proposal For Managing Pension Consultants (September 1, 2000)