BACK-SEAT prime ministers rarely produce the sweet music of political harmony and Rishi Sunak has to endure not one former premier delivering unhelpful instructions from the rear of his limousine but two.

This week began with an act of shamelessness, which almost defied belief; almost, because the person performing it was Liz Truss whose ability for self-awareness is non-existent but whose capacity to absorb ignominy appears boundless.

In a lengthy article and subsequent televised interview, the ex-PM could offer no apology or remorse for the economic mess she created but shamefully blamed, at various points, the Treasury, Downing St, the OBR, a left-wing “economic Establishment,” the IMF, US President Joe Biden, her party and the public.

The ridiculousness of it brought to mind the image of Kenneth Williams playing Julius Caesar in Carry on Cleo, when he complained: “Infamy, infamy, they’ve all got it in for me.”

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But, of course, all the self-delusional ex-premier had to do was look in the mirror to find the real culprit.

There is a reason why Ms Truss became the shortest-serving prime minister in history; she was hopeless, trashing Britain’s economic reputation, sending the pound tumbling, forcing the Bank of England’s emergency intervention and causing misery for millions of mortgage-payers.

Unhappily for Mr Sunak, his tin-eared predecessor has vowed to lead the fight for lower taxes, which doubtless means there will be another intervention before Jeremy Hunt’s March 15 Budget when he won’t cut taxes but inflation could well be lower and the Chancellor might, because of falling energy costs, not raise the cap from April as planned.

In one of her more remarkable comments, the Norfolk MP said she had no regrets about running for PM but didn’t aspire to be in Number 10 again. As if.

One Tory colleague branded her approach a “fantasy world,” saying it was “delusional politics and economics to suggest her agenda is in any way credible”.

Grant Shapps, the new Energy Secretary, gently pointed out that while, of course, the UK Government wanted long-term, lower taxes, Ms Truss’s agenda “rubs up against the reality of two or three years of Covid and the £400bn cost of that, followed by a war and the enormous cost and pressures of energy and inflation”. In other words, the seven-week premier put the economic cart before the horse.

While this week’s PMQs was unusually collegiate given it was about Ukraine, the SNP’s champion Stephen Flynn couldn’t resist the easy hit of noting the unhappy return of Ms Truss and offering Mr Sunak the chance to “apologise for the damage she's caused”. Looking somewhat uncomfortable, the PM declined the chief nationalist’s kind offer.

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Next month, we’re told Ms Truss will be giving a speech in Japan where she will warn about China’s growing threat and urge the West to be “better prepared” for conflict in the South China Sea. What could go wrong?

But, of course, there is also another predecessor sharing the back seat, who possesses an even greater inability to observe a period of longed-for silence.

Boris Johnson has, since leaving Downing St, been keeping up his profile by visiting the Republican leadership in Washington, meeting President Zelensky in Ukraine, and mixing with the movers and shakers at the Davos conference in Switzerland. Helpfully, his post-PM speeches have also enabled him to pocket several millions of pounds.

Mr Johnson, still hopeful of a return to Number 10, has been piling the pressure on his former Downing St neighbour over sending British jets to Ukraine and, apparently, while Mr Z was addressing MPs and peers in Westminster Hall on Wednesday, was constantly muttering under his breath about the person he regards as his nemesis: Mr Sunak.

Indeed, it seems Mr Johnson’s pressure seems to be working. After Number 10 weeks ago insisted sending jets to Ukraine was not going to happen, the PM has now ordered a feasibility study. “Nothing is off the table,” we’re told.

Earlier this week, Sunak sought to grasp the initiative by reconfiguring Whitehall with the unexpected creation of four new departments. But if it was aimed at inspiring confidence, it failed and merely launched a wave of Titanic deckchair metaphors.

Rejigging departments, which takes a lot of political time and energy, doesn’t inspire public interest, which is probably why it was well down the TV news bulletins.

One notable Cabinet appointment, however, was that of Greg Hands, a former Chief Treasury Secretary, who seven years ago led the UK Government’s fraught talks with Edinburgh over increasing Holyrood’s tax powers.

Mr Hands, who replaces Nadhim Zahawi, as party Chairman, insisted the party was “overall in good shape” but accepted it faced a “difficult” set of polls in May’s local elections in England. A whopper of an understatement.

Another notable appointment was his deputy, Lee Anderson, who has a reputation for straight-talking; always a dangerous trait in a politician. By sheer coincidence, in an interview Mr Anderson, who represents a Nottinghamshire red-wall seat, expressed support for bringing back the death penalty.

“Nobody has ever committed a crime after being executed. You know that, don’t you? 100% success rate.” Delicately put.

The Herald: Newly appointed Tory deputy Chairman Lee Anderson expressed support for bringing back the death penalty: 'Nobody has ever committed a crime after being executed. You know that, don’t you? 100% success rate'Newly appointed Tory deputy Chairman Lee Anderson expressed support for bringing back the death penalty: 'Nobody has ever committed a crime after being executed. You know that, don’t you? 100% success rate' (Image: Newsquest)

The PM quickly distanced himself from his colleague’s remarks, saying: “That’s not my view, that’s not the Government’s view.”

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The deputy chairman’s brusque approach to politics might mean Mr Hands, who described his Conservative chum as a “great asset,” spends more time than he would like clarifying his colleague’s remarks to the media.

If Mr Sunak is going to negotiate the Conservative carriage around all the road bumps between here and the next election, then he will have to somehow try to ignore or even silence those siren voices emanating from the back seat. Good luck with that one.

It looks like the journey over the next 18 months to polling day is going to be a very long and arduous one for the real PM and the ultimate destination – no thanks to his obstreperous passengers – may not be the one he is dearly hoping for.