Aidan Smith's TV week: Litvinenko (ITVX), Strike (BBC1), Bad Education Reunion Special (BBC3)

There are three David Tennants in our house. Two on my 11-year-old daughter’s tablet - the Paisley-born star plays twins in the Nativity! movie she’s watching while off sick from school. I call her through from her bedroom to see the third - bald, sunken eyes, hospital tubes everywhere.

David Tennant as Alexander Litviinenko.

“That’s not him!” she says. Oh yes it is. Actors hate being typecast, I tell her, and if there’s a role that’s further away from the dual one of competing teachers in a jolly comedy about a Christmas carol contest then it must be Litvinenko. (Actually, impersonating Dennis Nilsen was probably more of a leap but I don’t mention that).

This ITVX four-parter reconstructs the astonishing events of 2006 when Alexander Litvinenko, the former KGB spy, was assassinated in London - and begins with an astonishing statement to the police: “I need to report a murder. Mine.”

Litvinenko knows he’s been fatally poisoned but the Met think he might be mad. He’s passed between departments until the two detectives assigned to the case activate a tape recorder in the emergency ward and in a faltering voice he says: “I can start this. Tomorrow I will be tired. In two days, worse. Three days … ”

Holliday Granger and Tom Burke in Strike.

One tec says to the other: “If he’s a nutter then he’s the most level-headed nutter I’ve come across, and I’ve met a few.” Litvinenko tells them about Section 7 which he ran. “Top secret department, simple job: to kill.” Who? “Enemies of state. But I refused. Job is not human, it’s corruption. I write a book, they are angry, I am trouble-maker.” Who is “they”? “Vladimir Putin, former head of KGB.”

That word again: it’s an astonishing performance from Tennant. Almost all of it is done from bed so he’s really only using those caved-in peepers. His Russian accent is odd, they say, and sounds too much like Jose Mourinho. Who are “they”? TV previewers. The real nutters, I reckon - it’s spot-on.

Litvinenko’s widow Marina is played by Margarita Livieva and when the case is taken up by the counter-terrorism boys, Mark Bonnar is in charge. He’s shaved off that silver swish, virtually omnipresent on my telly these days, maybe so that his countryman Tennant feels less naked. When lab tests come back Bonnar’s Det Supt Clive Timmons thinks he should correct them. “Plutonium?” “No, Polonium 210, an isotope, extremely rare - the most dangerous substance known to man.” It was snuck into a pot of tea.

I’ve been mean about Strike (BBC1) in the past but it might be growing on me. There’s no obvious justification for this because the new series begins with some over-familiar Cornish scenery before the eponymous gumshoe hero played by Tom Burke - still looking like his shabby coat wears him and still mavericky - returns to his gloomy office with its wood panelling and frosted glass which seems to be a tribute to The Maltese Falcon.

Jack Whitehall with Charlie Wernham and Ethan Lawrence in Bad Education Reunion Special

Thinking about that movie classic, one of Humphrey Bogart’s hard-boiled lines as private eye Sam Spade was: “You’re a good man, sister.” It’s just as well JK Rowling, who pens the Strike whodunnits as Robert Galbraith, has not revived it. She’s already in enough bother.

Troubled Blood is based on the book which was accused of transphobia when published two years ago. A serial killer disguising himself as a woman caused the upset, but there was also criticism of the critic who claimed the moral of the tale was: “Never trust a man in a dress.” This character, it was pointed out, wasn’t portrayed as trans and Rowling never called him a transvestite. The issue is swerved in the screen version.

Even so, it may be best not to say of Strike’s sidekick Robin (Holliday Grainger): “You’re a good man, sister”. This despite her being proactive and brave in the investigation into the disappearance of a London GP in 1974 and confronting the Don Corleone wannabe and his son who might know something about it.

The serial killer, still alive but not yet encountered by our duo, kept severed limbs around the house during his reign of terror. This seems particularly grisly for Strike, almost as if Netflix’s bloodlust has, er, forced its hand.

But the doctor is/was fascinating - bunny girl, feminist and brave herself. There are funny incidental characters and cute cameos and it’s good to see Cherie Lunghi again. Ruth Sheen, part of Mike Leigh’s repertory company, has some cutting quips as the detective agency’s Man Friday (hang on, can I still use that term?). But the reason I think I’m warming to Strike is old-fashioned, corny and sentimental.

Will the principals get together? This is the real drama. Early on, there was more chance of Strike removing his coat but Robin no longer irritates him, nor he her. She’s sympathetic of him and he’s protective of her. Ah, but if they did start a romance surely it would be show over.

Bad Education Reunion Special (BBC3) is Jack Whitehall’s farewell as hopeless teacher Alfie Wickers who in the opening scene has been taped to a whiteboard by his class which seems fair punishment for that man-bun. At my school I never did that – this wasn’t the era of whiteboards or man-buns – but was complicit in a history master being locked in a store cupboard. This is an interesting juncture for school-based shows: Ackley Bridge has just finished, Waterloo Road returns next month and this one will resume with two ex-pupils stepping up as teachers. I still see room for a revival of the greaest of them all, Please Sir!