Matthew Norman: Ken's sacking must surely be on Cameron's Christmas list

The autocratic Mrs Thatcher would have fired Clarke in an instant for brazenly challenging her on fixed sentences for knife crime

In the week it was officially declared that the centre of political gravity has shifted so far to the right that we are all Thatcher's Children now, how apt that the spotlight rests on the assassin chiefly credited with (or blamed for) her matricide. It was 20 years ago not quite today that Kenneth Clarke spearheaded the Cabinet insurrection that did the old girl in, and if the gossip is accurate he is about to be executed himself by David Cameron.

Rumours of Ken's imminent political death may, of course, be exaggerated. Nobody survives at the top of the fetid Westminster pond for three decades... well, there simply hasn't been a survivor in Ken's league (not even that slithery servant Jack Straw) in our lifetime. Under Thatcher and Major, the adorable bruiser held a range of potentially lethal portfolios – Employment, Health, Education, Home Office and Chancellor – and bulldozed his way through them all.

Losing the first of his three cracks at the leadership to William Hague in 2001 would have driven a less stoic chap to spend more time with his bird-watching binoculars. Losing the second, to Iain Duncan Smith, would have sent anyone else into intensive therapy, or even to the study with a balloon of brandy and the trusty Luger.

Those humiliations Ken blithely brushed off, the Tory contempt for him and his fancy Europhile ways more than matched by the affection he still induces in the wider electorate. Knowing this, David Cameron should have had the courage to make him shadow Chancellor after George Osborne's holiday from hell on Corfu. Speculating on how differently things would have developed had he done so is an intriguing what-if. For what very little it's worth, my guess is that the Tories would have won a majority of 30-50, introduced less ideologically-driven and incendiary spending cuts, put the Labour Party in even graver schtuck than it is, and safely shepherded Nick Clegg back to the opposition benches to rail furiously against the trebling of university fees he now assures us is "the right thing to do".

Instead, largely through loyalty to the Bullingdon chum known to that dining club as "Oik", Mr Cameron chose to resurrect Ken first as shadow Business Secretary; and then in May, when he needed that post to keep Vince Cable occupied in moments carved from practising his foxtrot for Christmas telly, brought him into the Cabinet as Justice Secretary (and Lord Chancellor).

With all the fearlessness of a 70-year-old liberated from dreams of becoming PM (not that he gave a stuff about ingratiating himself with anyone when young and ambitious), Ken has done something no Cabinet minister had dared to do in an eon. He has stated, in the plainest of terms, what he believes. Prison not only doesn't work, he insists, but exacerbates criminality at enormous public cost. It should ideally be a last resort for the violent and recidivist, while judges – with arguably better insight into individual cases than even the most gifted telepath writing leaders for The Sun – should have the freedom to vary sentences according to the facts, rather than prosecuting the Government's masterplan to assuage those leader writers and callers to radio phone-ins.

As for the hysteria when a prisoner who would have stayed banged up under current guidelines commits a serious offence within a fortnight of being released, Ken goes on, so be it. There is no such thing as a guarantee in this life (I paraphrase a touch), and always a price to pay for enlightened policy.

The reaction to Ken's musings, doubtless intensified by residual bitterness over that matricide, has been predictably livid. Apart from with that tiny rump of us who dwell in the darkness on the bleeding-heart, woolly-minded outer reaches of the liberal left, there is little affection for Ken's penal policy. The facts that there is no money to build new prisons (or even properly maintain existing ones), that the service is largely dedicated to containing the mentally ill and drug-addicted to relieve the strain on the NHS and social services, and that every scrap of important research suggests that the Scandinavian model is more successful at reducing crime than the American one, do not scratch the surface. This is an emotional issue, and here in retrograde Britain the urge for retribution will always trump cold logic.

So it isn't hard to understand why the sudden disappearance of Ken Clarke must feature near the top of David Cameron's Christmas wish-list. Assuming Santa fails to oblige by dropping a cluster bomb down a Nottingham chimney, whether the PM treats himself to that gift in the new year sales – there is talk of a mini-reshuffle in January – will offer a useful hint about his chances of developing into a good prime minister.

Will he frank the New Labour form by succumbing to tabloid pressure at every turn, or does he have the gumption to sit out a passing tornado? So far as the crude power struggle at the heart of his regime, is the string-'em-up populism of media supremo Andy Coulson a stronger influence than the progressive leanings of chief strategist Steve Hilton? Does he have the self-confidence to allow senior ministers their independence, or the monomaniacal brittleness that led Mr Tony Blair to reduce them to obedient technocrats ? Will the long-term strategic imperative to placate the Liberal Democrats by balancing the fiscal rightwingery with liberalism on social policy outrank the desire for short-term tactical gain?

Ken Clarke is the very last politician to be blown around by political winds, yet he is cast against type as a weather vane. By keeping him, Mr Cameron would make the statement of intent that he would rather tolerate dissent from senior ministers than be bullied by the forces of reaction. By sacking him, he would look weak and pliable in pursuit of looking strong and resolute, and ridicule his commitment to being what the Americans call an agent of change.

The autocratic Mrs Thatcher, who divided the world into them and us, and casually jettisoned Francis Pym for questioning the democratic benefits of a huge parliamentary majority, would have fired Ken in an instant for brazenly challenging her on as incendiary an issue as fixed sentences for knife crime. We may all be her children today, but as I hope Mr Cameron will underline by retaining Ken Clarke, that doesn't mean we must always behave like Mummy.