“Good grief!” among other, less polite exclamations, seems to have been the general reaction to the news that Kenneth Branagh is to play Boris Johnson in a five-part Sky drama, 'This Sceptred Isle', about Johnson’s premiership and his (mis)handling of the Covid pandemic.

Various Twitter wags mooted Mr Blobby as superior casting, while others suggested Matt Lucas, who has delivered wickedly accurate impersonations of the PM and his mixed messages on The Great British Bake Off and elsewhere. Another tweet asked whether Branagh would be missing the first five script read-throughs – a witty reference to Johnson failing to attend five Cobra crisis meetings in the run-up to the Covid pandemic – while others have wondered how much the PM paid for such flattering casting.

Johnson has been portrayed before, of course – by Christian Brassington in the 2009 drama about his and David Cameron’s Oxford years, 'When Boris Met Dave', and more recently in Channel 4’s 'Brexit: the Uncivil War', where he was played by Richard Goulding (best known for playing fellow Old Etonian, Prince Harry in 'The Windsors'). But Boris was incidental to James Graham’s take on the 2016 referendum, which focused on the Vote Leave strategist Dominic Cummings.

How many had heard of Cummings before he was played by Benedict Cumberbatch? And we can only guess the effect on his ego of being portrayed as a Machiavellian genius by the man who was Sherlock. You wouldn’t maybe draw a direct line between Cummings’s lockdown-breaking visit to Durham last May and his screen portrayal, but it must have added to his sense of invulnerability.

How easy is it to play a well-known politician? The most feted recent practitioner is Michael Sheen, who has portrayed Tony Blair three times: in 'The Deal', about the Blair-Brown pact (with David Morrissey as Gordon Brown), in the 2006 movie 'The Queen', and in 'The Special Relationship' (with Dennis Quaid as Bill Clinton).

“You do have to meet the audience’s demand for familiarity with the character,” Sheen has said. He certainly has the talent to tease out any inner depths, but largely we’re in the realms of surface impersonation. Alec Baldwin has spent four fruitful years spoofing Donald Trump on Saturday Night Live, but the performance, while amusing, goes no deeper than Lucas mimicking Johnson – and may even have the unwanted side-effect of softening attitudes where real-world accountability is needed.

That’s what makes the combination of Branagh and writer-director Michael Winterbottom so intriguing. The tousle-haired, bloviating Boris Johnson is largely a construct – he’s a performer, and who better to understand him than our most self-consciously actorly actor?

And Winterbottom is a serious and adventurous filmmaker, well-known for his collaborations with Steve Coogan (on 'The Trip' and elsewhere) but whose range also takes in Jim Thompson, Naomi Klein and Thomas Hardy as well as hard-hitting subjects such as the Siege of Sarajevo, the refugee crisis and Guantanamo Bay. He might well find the artistic means to expose deathly incompetence.

Winterbottom is co-authoring with Kieron Quirke, a comedy writer whose hits include 'Cuckoo' and 'Defending the Guilty', but let’s hope this new drama doesn’t stray too far in that direction.

With 100,000 already dead, a steady hand is required on the ridicule. In fact, there’s Winterbottom’s opening scene: Branagh as Boris, unkempt head-bowed, and being “deeply sorry for every life lost”. Cut to one year earlier…