A big division exists between official ethics watchdogs, such as the Committee on Standards in Public Life, and the Government. Should the Prime Minister be both judge and jury of the Ministerial Code, the official guide to conduct and the handling of financial interests? Or should there be an independent adviser to ensure transparency? In short, who guards the guardians?

This issue has produced frequent political storms since 1997: over the Bernie Ecclestone affair, and the Peter Mandelson and David Blunkett double resignations.

The standards committee has sought to strengthen the code. Its report in April 2003 urged the creation both of an independent adviser on ministerial interests to assist incoming ministers and, separately, the appointment of two or three senior individuals at the start of each Parliament to investigate misconduct charges.

Tony Blair could have saved himself a lot of trouble, and possibly a couple of resignations, if it had adopted these proposals. In September 2003, the Government partially accepted the principle of an independent adviser, although only to supplement the work of permanent secretaries. Nothing has happened since then. Ministers may, however, have something to say tonight in response to a Tory-initiated Commons debate, where the energetic Chris Grayling will call for such an adviser. Mr Blunkett might have avoided his “misunderstandings” over the code if he had been able to call on such an adviser.

Quite separately, Mr Blair and Lord Turnbull, the former Cabinet Secretary, resisted calls for an investigatory panel, arguing that it is up to the Prime Minister to decide, case by case, whether an inquiry is needed. But an ad hoc approach tends to be unsatisfactory. Sir Alan Budd, the Government’s former chief economic adviser, who inquired into the Home Office handling of the first Blunkett row, was just the type of person who would be on such a panel. But the process then was messy.

Moreover, the lines of responsibility are blurred. Only a fortnight ago, Mr Blair said Mr Blunkett was not guilty of any impropriety, even though he had clearly broken the code.

After the Blunkett affair, Sir Alistair Graham, the chairman of the standards committee, renewed the call both for the investigatory panel and for a review of the code. Mr Blair remains opposed. He said last week that “the only person who will decide who is in the Government in the end is the Prime Minister and you can’t subcontract that decision”. But that blurs two distinct questions. No one disputes that the Prime Minister should decide what happens to ministers. This is rightly a political judgment. But that is separate from establishing the facts. That is the role for an independent investigator.

The government position may be shifting. Sir Gus O’Donnell, the new Cabinet Secretary, is worried about loss of trust in public life and takes these ethical issues more seriously.

He intervened publicly in the Blunkett affair to say unambiguously what the code meant and how it had been broken. Whitehall watchers are waiting to see whether Sir Gus prevails over Downing Street’s caution. Remember, also, that Gordon Brown has for several years favoured an independent ethics adviser.

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