David Cameron "almost certainly" breached the ministerial code by failing to call in his independent adviser on ministers' interests to investigate allegations against former Defence Secretary Liam Fox, a Whitehall watchdog said on Tuesday.
Dr Fox resigned last year after being found guilty of breaching the code in his relations with friend Adam Werritty, following allegations which were initially investigated internally by the Ministry of Defence and then by Cabinet Secretary Sir Gus O'Donnell.
The prime minister's former adviser on ministerial interests Sir Philip Mawer, who quit the post shortly afterwards, has expressed his "frustration" that Mr Cameron did not call him in to handle the case.
The chairman of the Committee on Standards in Public Life (CSPL), Sir Christopher Kelly, said today he shared Sir Philip's concerns.
Sir Christopher called for a change in the rules to allow the adviser on ministerial interests to launch inquiries on his own initiative, rather than having to wait for the Prime Minister to ask him to investigate.
The CSPL chair told the House of Commons Public Administration Committee: "On this occasion, I think he should have been employed. Indeed, I think it was almost certainly a breach of the ministerial code that he was not employed.
"The view of the Committee (on Standards in Public Life) is that there is advantage in this post existing and if it is going to exist, it has to be used in the way that was envisaged.
"Just like the parliamentary commissioner (on standards), the adviser should be able to initiate inquiries of their own where there is a prima facie case to investigate, whereas at the moment he is only able to do so at the request of the Prime Minister."
Sir Philip was the first holder of the adviser's post created by former PM Gordon Brown in 2008. He was given a remit to conduct inquiries into possible breaches of the ministerial code but could do so only when requested by the Prime Minister, and the Prime Minister retained the power to decide whether a minister should keep his job if a breach is committed.
Sir Philip cleared former justice minister Shahid Malik of allegations relating to his office rental in 2009 but was not called upon to conduct any other investigations and resigned at the start of this year, to be replaced by Sir Alex Allan.
Speaking to the Public Administration Committee shortly after his departure, Sir Philip denied he had quit the post in anger at Mr Cameron's failure to call him in but said he would have liked to have conducted a "quick and dirty" inquiry into the allegations against Dr Fox.
"I believe that the adviser ought to have been brought in and ought to been brought in pretty well from the outset. That is my view," Sir Philip said in January.
"I was frustrated at the failure to call me in and I made clear to the Cabinet Office that the credibility of the role of the adviser had not been assisted. It was a missed opportunity and I regret it.
"I made my views very clear to the Cabinet Office and to the Cabinet Secretary."Suggest a correction