Today should mark the announcement of PM David Cameron's first Cabinet reshuffle.

Political geeks are duly excited. Cabinet ministers are duly nervous.

......................................................................

Click here for details of The red ties that bind Comrade Sir David: postmodern NHSCB to commission itself (oh yeah, and what cowboy drafted this mandate?), the new issue of subscription-based Health Policy Intelligence.

......................................................................

Media outlets as ideologically diverse as the Daily Mail and The Guardian are speculating on a 'shock' Cabinet exit for Andrew Lansley (saviour, liberator).

The FT concurs, and The Times leader even resurrects the idea of giving health to Vince Cable (which they first aired last April): spectacularly unlikely, given that health is a high-profile, spending ministry, and thus a Tory fiefdom in the Coalition arithmetic.

The Telegraph has become a first-choice leak-receptacle for the Tory party in coalition, and puts Mr Lansley in the 'might move' category.

This is fast-moving and uncertain turf. And my form on predicting Mr Lansley's tenure in office, having dubbed him 'Secretary Of State For The Time Being', can only be described as patchy.

That said, here is why I think Mr Cameron is unlikely to move Mr Lansley. (EDIT: and I was wrong - see here for more)

1. Loyalty, famously 'the secret weapon of the Conservative Party'. Mr Cameron has had ample opportunities to jettison Mr Lansley throughout the tortuous passage of the Health And Social Care act, yet did not do so.

Some of this may be a recognition that his understanding of the Lansley plans (which as the essential Nick Timmins book 'Never Again?' notes, were sold pre-election under the party motto of 'radicalism on education; reassurance on health') was poor - as was that of 'Tory policy brain' Oliver Letwin.

No small part of this will be the fact that Mr Cameron and Mr Osborne were both employed in their first political jobs by Mr Lansley in the Conservative research department.

2. Loss of face - when trying to rescue the NHS reforms in the early spring and then in the pause summer of 2011, David Cameron expended considerable political capital on trying to sell the reforms.

In doing this, Mr Cameron made numerous statements about the NHS reforms that would be powerful hostages to fortune.

This is not to say that there has been no disquiet in Number 10 about Mr Lansley's performance, as we reflected on the infamous 'taken out and shot' Times briefing back in February.

Number 10 attempted The Calais Defence of the reforms, to little effect.

It is not unknown for the Government's policies to u-turn: we have seen them on privatising forests and on pasty taxes. The NHS reforms are different by several orders of magnitude. These are Mr Lansley's reforms to a massive degree.

If Mr Cameron chooses to dismiss Mr Lansley, then in so doing he also chooses to disown the reforms at a time when the old system is very definitely dead, the new system is not yet born and the intermediate system is the Nicholson Health Service, centralising power under the Comrade In Chief to a degree previously never seen.

3. Irreplaceability - longstanding readers will know that Health Policy Insight has long been campaigning to see Health Minister Simon Burns installed in the top job.

However, the Timmins book 'Never Again? thrice-quotes Mr Burns' timeless line on the reforms that "you cannot encapsulate in one or two sentences the main thrust of this".

Mr Lansley's NHS reforms are now the law. They are complex, and in places confused and contradictory - and have few authentic understanders, let alone supporters, in the pool of likely candidates who could replace him.

For Mr Cameron to have supported the reforms all the way, and yet now to discard their architect, would be scarcely comprehensible - in either political or practical terms.