David Cameron says today he will restore the ‘independence’ of the civil service. I passionately hope he does not become Prime Minister, but if he did, I would advise him to learn the difference between ‘independence’ and ‘impartiality.’

The Civil Service has a duty to be impartial. That is not the same as independent.

An impartial civil service – ie one which supports the elected government in the devising and implementation of policy in a non-party political way – is a good thing, and for all the Tory and media claims to the contrary, I do not accept that we politicised the civil service. It is a matter of some pride to me that of all the people who have had a go at me for my time in Number 10, none of them were the civil servants who worked directly to me.

Government is political. Ministers are – or should be – political. Political advisors are political. Civil servants are not.

An independent civil service is an altogether different concept. That would be a civil service that did not feel any responsibility to work towards the agreed priorities of the elected government. A civil service with its own agenda. A civil service with permission, in effect, to be the very thing Cameron says he wants it not to be – political.

The vast bulk of civil servants do a good job. I met some truly exceptional people in the civil service who, had they chosen a different path, could have earned vastly greater rewards in the private sector, but who have a real belief in the concept of public service. I met many many more who were good professional people. And I met some who were not up to much. So the same as most walks of life.

But there were definitely times – I think mainly of some of the government’s efforts to tackle crime and anti-social behaviour, and other incidents when civil servants were not adequately supporting ministers under fire, and even working against them – when a minority did appear to confuse independence and impartiality.

I can see why, for political reasons post smeary emails, Cameron prefers to talk about this, or expenses, or a call for TV debates, rather than face up to some of the public spending and other policy decisions he is going to have to confront before an election. I can see too why he might think a big tribute to mandarins will go down well in Whitehall, and add to the mood of inevitability he wants to create that he is destined for Number 10.

But if he ever got there, he would be well advised to understand the difference between impartiality and independence, and make sure the civil service does too.