In Whitehall, those stuffy civil servants are quaking with fear as Tony Blair gets set to torch their rotting citadel

The problem with Tony Blair is that - even though he went to a proper public school and Oxford - he has somehow never understood the merits of the self-perpetuating oligarchy.

Let me appoint myself (although I attended only a humble north London comprehensive) cipher for the society of past and present permanent secretaries, those men - for they are mostly men - who provide the ballast of government while the flotsam and jetsam of politicians ebb and flow on the tide of fickle electoral opinion.

Blair is proposing to unman their very leader, the cabinet secretary and head of the civil service. The Prime Minister's idea is that when the current incumbent, Sir Richard Wilson, goes in the late spring, he will split the job in two. There would be a head of the home civil service, in charge of all that management stuff. The responsibilities would be recruitment, promotions, efficiency, improving the delivery of services and all those important things that civil servants usually abhor. And the other job, cabinet secretary, would be the sexy one. It would be all about policy-making and endeavouring to bring harmony to dissonant voices in cabinet.

Wilson and chums regard such reform with horror. For them, it would represent a throwing open of the gates to the barbarian hordes. Decades of alleged civil service impartiality would be undermined. We would witness full-blooded politicisation of the machinery of government, new-Labour style.

Why would civilisation as we know it crumble? The reason is that the head of the civil service would lose the ear of the Prime Minister. Whatever his intentions, however much he may obsess in public about the importance of "delivery", Blair would never spend much time in a tete-a-tete with the worthy admin guy in charge of salaries and paper clips. So the home civil service head would find it much harder to lobby the PM in defence of the status quo.

My problem with this argument is that the extensive powers of Wilson, with his dual role, do not seem to have helped him much in the struggle with Blair's guerrillas. Everywhere I look, I see political appointees: some as special advisers, many holding down mainstream civil service jobs.

It is a bugger's muddle. With the proliferation of policy units, planning units, performance units, strategy units and cabinet secretariats, it has become almost impossible to work out who is responsible for what in government. Indeed, there is absolutely no reason for Stephen Byers to worry about John Birt taking an interest in the railways, because another consultant with an identical brief is bound to be along right after Birt shunts into the sidings.

For what it is worth, Wilson has told friends that, before the last election, Blair was planning changes supposedly much worse than this, and that he has preserved more honour for Whitehall than is commonly recognised. But if that were really so, then Wilson should have abandoned the habits and customs of his cadre and gone on the record about this threat to democracy.

There are, I think, persuasive arguments for bifurcating the top Whitehall post. The skills of managing a vast bureaucracy are very different from those of mopping the brows of the policy-makers at the centre of government. My impression, however, is that Blair's strongest reason for the reform is that he cannot identify anyone with the appropriate skills to do both jobs.

He would like to bring in an outsider, or appoint some kind of reformer, because he has a pretty low regard for the way that Whitehall has traditionally handled itself. On the other hand, the people he trusts have told him that appointing a business person as Wilson's successor, or even a younger chief civil servant, would be a disaster: "The system would have him for breakfast", was how a Blair adviser put it.

If Blair were to split the posts, possibly one of them could go to a less predictable candidate. I would guess that a newcomer would have better survival prospects in the cabinet secretary position. Unfortunately, it is the other job, that of modernising Whitehall, that calls for outside expertise.

So who are the people likely to put themselves forward, or be thrust forward, for one post or the other? In no particular order, they are:

- Sir David Omand (former home office perm sec, back from illness, the oligarchy's preferred candidate);

- Sir Andrew Turnbull (personable Treasury perm sec, perhaps a bit close to retirement, a possible transitional appointee);

- Jeremy Heywood (wunderkind, ex-Treasury, Blair's principal private secretary - loved by the PM; probably too young);

- Sir Howard Davies (chairman of the Financial Services Authority, highly regarded with ill-disguised envy by most civil servants for his PR skills and job-hopping career; says he doesn't want it, but Whitehall refuses to believe him);

- Robin Young (unorthodox new perm sec at the Treasury, probably not sufficiently anally retentive);

- Richard Broadbent (ex-merchant banker turned head of Customs and Excise - a de facto outsider).

You may notice that there is not a single woman on this list. I could have included the impressive Rachel Lomax, permanent secretary at the Department of Work and Pensions, as a sign of how liberal and open the civil service has become. But everyone tells me she is not really in the running - one more reason why I think Blair should torch the entire, rotting citadel. Time to raze and rebuild.

Robert Peston is editorial director of Quest(TM); www.csquest.com; e-mail rpeston@csquest.com