Sir John Chilcot, chair of the inquiry into the Iraq war, has urged senior officials to "take their courage in both hands" and be more willing to challenge ministers on decisions they disagree with.
Chilcot's long-awaited report into the build-up, execution and aftermath of the controversial 2003 invasion of Iraq was finally published earlier this year.
The report criticised former prime minister Tony Blair for sidelining his cabinet and instead relying on a close-knit team of advisers, and said key departments involved in analysis about the likely impacts of invasion had failed to share information or adequately weigh up the risks.
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A Whitehall-wide "lessons learned" exercise is currently being led by the Ministry of Defence, and Chilcot – a former senior civil servant – on Wednesday told MPs on parliament's Liaison Committee that top-ranking officials needed to be bold in challenging ministerial decisions to avoid a repeat of the Iraq mistakes.
"If I have a purpose today it is to encourage all my successors as colleagues at the top end of Whitehall to take their courage in both hands and insist on their right to be heard and to record what their advice is, even if that advice is not taken," he said.
"It's entirely for ministers to decide. But it is for senior officials – and I would include the senior military as well in this – to state very clearly their best advice to their masters. And I think the recording of that advice, and the recording of any discussion about it is absolutely central.
"That guarantees, if you like, a degree of willingness to challenge, a duty to challenge, which in a sofa [government or] den setting simply isn't there."
Earlier this year, cabinet secretary Sir Jeremy Heywood rejected calls from the Better Government Initiative (BGI) – a think tank made up of former top civil servants – for officials to be given the right to inform parliament if they believe ministers are ignoring the principles of cabinet government and failing to consult colleagues on major decisions.
"It is about leadership" – Sir John Chilcot
The BGI — whose members include former cabinet secretary Lord Butler, and the ex-Ministry of Defence permanent secretary Sir Richard Mottram – said there was a "strong case" for extending the present system of "ministerial directions" to also cover breaches of the Cabinet Manual, going beyond their current limited use in challenging spending decisions.
But Heywood, currently Britain's most senior civil servant, said such a system could lead to a breakdown in trust between the prime minister and their top official, warning could "destroy their relationships, frankly".
Chilcot struck a cautious tone at the Liaison Committee when pressed on the BGI's recommendation, saying that while he had "a little sympathy" with the plan, it was ultimately for parliament and cabinet ministers "to enforce their own accepted set of conventions and rules".
The Iraq inquiry chair said his own experience as an ethics adviser to the intelligence services had led him to believe that confronting questionable decisions required more than just the threat of public disclosure.
"The only way to satisfy someone who is, in conscience, deeply dissatisfied with the institution and its workings that he or she is part of is to talk it through with the leaders of that institution," he said. "It is about leadership."
"Challenge"
Committee member Bernard Jenkin meanwhile pressed Chilcot on the structures needed to ensure an "atmosphere of challenge" in the civil service, including whether the National Security Council – set up by David Cameron in 2010 in a bid to improve the coordination of departments' work on security issues – needed its own independent analysis and assessment unit, rather than relying on information provided by the rest of Whitehall.
Such a move would, Jenkin argued, raise its status above that of "a glorified Cabinet committee".
Chilcot cautioned against a focus on the "machinery of government", saying that "structures and institutions" were "all very well" but were "not by any means enough" to create a culture of challenge.
"It's the people and the way that they work that really matters," he said. "And if they work well enough you may not need to muck about with the structures too much, because that's disruptive quite often."
He argued that "real cooperation between responsible departments at every level, ministerial and official" could bring about proper scrutiny of decisions "in the absence of that formal capability".