PETER Mullan. A raging bull in Tyrannosaur, an absolute swine in Top of the Lake, a voice you could grate carrots on and a face with more crevices than Ben Nevis. As romantic heroes go, you are more likely to find Mullan diving into a toilet with Trainspotting’s Renton than following Mr Darcy into a lake. Am I right?

Wrong, wrong, and wrong again. Catch him in the wonderful Mum (BBC2, Tuesday, 10pm) and you will see Mr Mullan is really a big smoothie chops who has clearly been hiding his true nature for fear of coming down with a bad case of the Hugh Grants. As the maybe-someday boyfriend of widowed Cathy (Lesley Manville), Mullan’s performance is as satisfying as everything else in Stefan Golaszewski’s perfectly tuned piece about a family finding their way through loss. It is a tough gig to make a comedy out of such circumstances, but with just the right blend of light and shade, and a generous slug of spectacular swearing from grandad, Mum brings home the bacon.

Having given us torture and dullness in Gunpowder and found it was nobody’s cup of Saturday night tea, the BBC has turned to something completely different in Troy: Fall of a City (BBC1, Saturday, 9.10pm). Here was a swords and sandals drama with added sex (two bare bottoms in the first 15 minutes, not that anyone was counting) and a hint of sapphism. Drawing its inspiration from Homer and the Greek myths, all this titillation was strictly for educational purposes, so that is okay.

The first instalment told the tale of Paris, a thrusting young buck who went from Troy to Sparta and fell in love with the Queen instead of the daughter he was supposed to marry. Now I am no Mary Beard, that vacancy is filled, but I am getting the sense this shack up does not work out well. Not if Cassandra, looking into the distance and screaming every five minutes, is any guide.

Homeland (Channel 4, Sunday, 9pm) returned for a seventh series and everyone’s favourite Cassandra of the CIA was back in the shape of Carrie Mathison (Claire Danes). Admittedly, Carrie has had a lot to fret over recently, including saving the country’s first woman president from assassination, only for said commander-in-chief to turn into a tyrant.

Elizabeth Marvel makes a very scary elected dictator, all rage and righteousness. Saul (Mandy Patinkin), languishing in jail, needs Carrie at the top of her game to sort this mess out, but the strain is already starting to show. If Carrie doesn’t pull her finger out it could be left to the psycho shock jock Brett (Jake Weber) to rescue the country, and that would never do.

A lot of viewers lost faith with Homeland after the Nicholas Brody story ended, but the last series snapped things back into shape, not least because the writers did not go for the obvious story of a big blowhard taking over the White House and scaring the bejeezus out of the world. As if that could ever happen.

The week’s most riveting drama was to be found not in Sparta or DC but in a documentary set in Bedfordshire. 24 Hours in Police Custody (Channel 4, Monday, 9pm) started with a compelling enough case, that of a man who was being blackmailed after visiting a prostitute, but ended up with a corker of a story when the miscreant demanding money was unmasked.

Ever wonder what The Big Bang Theory’s Sheldon was like as a child? That’s handy, because Channel 4 has just bought an entire series to explore the subject. With its family setting and generous deployment of the music of the time, Young Sheldon (E4, Thursday, 8.30pm) is a kind of The Wonder Years for millennials. It also has a star in the making in Iain Armitage who plays the nine-year-old genius getting ready for his first day at High School. It is East Texas, 1989, and Sheldon has bought a bow tie to wear. How could he not fit in?

Young Sheldon will likely function as a sort of X-Files for hard core Big Bang Theory fans. Within this series could lie the answers to the questions they seek, such as when Sheldon swapped bow ties for T-shirts, and why he has such a scratchy relationship with his family. Or you ignore all that and just enjoy the comedy as the budding theoretical physicist learns to deliver his trademark killer put-downs. As with the adult Sheldon, there are just enough outbreaks of sweetness to make you love him, despite everything.

But he has rivals for our affection, chief among them his twin sister Missy who wants to watch trash TV while Sheldon is after something more educational. “It’s TV,” drawls Missy. “We aren’t supposed to learn.” And folk think Sheldon is the smart one.