In Nicholas Hytner’s memoir of his time in charge of the National Theatre, there is a very (possibly unintentionally) funny description of the audition of Benedict Cumberbatch, an actor then somewhat less famous than now, for the part of Frankenstein’s monster. Boy, did he give it his all. The mewling and grunting lasted for some 25 minutes, a period during which Hytner, hoping it would come to an end soon, found himself breaking into a sweat. Cumberbatch, though, was not to be put off. Only when the director, Danny Boyle, finally intervened and thanked him for his time did he stroll off to get ready for the Terence Rattigan in which he was starring that night.

I thought of this as I watched the first episode of Patrick Melrose (9pm, 13 May), David Nicholls’s adaptation for Sky Atlantic of Edward St Aubyn’s sharp and powerfully moving quintet of novels about an upper-class heroin addict living in the long shadow of his monster of a father. Nicholls has switched things around, beginning his series with the events of Bad News, the second novel, for which reason we meet Patrick Melrose (Cumberbatch) first in the early 1980s in New York, where he has gone to retrieve his father’s ashes. It’s an ordeal with which he can only cope by consuming copious amounts of drink and drugs.

To say that Cumberbatch embraces the role of the shivery, shaky, sometimes half-comatose addict is a bit like saying Kim Kardashian has embraced fame. Here, again, is Frankenstein’s monster, except this time he rolls around not on the stage of the National Theatre, but on the floor of a hotel bathroom, a creature brought to life by a needle to a vein. His slow drawl is, of course, pure Terence Rattigan. Even Boyle haunts the piece, for this is basically Trainspotting (a movie he directed), with better shoes and more sophisticated small talk.

I think Nicholls’s decision may make Patrick Melrose hard to love for those who haven’t read the novels; the danger is that they will leave after the first episode, exhausted by its hyperbolic pace and sneering wit (“Is it Dad?” he cries out to an imaginary crowd in the mortuary, ripping the tissue from his father’s face as if he were a birthday present. “It’s just what I wanted. You shouldn’t have!”). Why, they will wonder, is this man so ghastly, so sad, so inept even at a straightforward thing like grief?

But I hope they won’t. The second episode, which flashes back to 1967 when Patrick is a withdrawn child in Start-rite sandals, and of which I have seen a preview, is much better than the first: a brilliantly written and magnificently paced display of distilled human horror. Hugo Weaving, who plays Patrick’s father David, steals every scene; 30 minutes in and you’ve only to catch sight of his velvet slippers to feel like puking. Pip Torrens, for all that he has to wear a silly Bucks Fizz wig, is also wonderful as David’s ghastly friend Nicholas, an old Etonian who covers his own fear of the man by ruthlessly competing with him in matters of snobbery and cruelty.

Everything is opulent, and everything is desperate: just right, in other words. St Aubyn’s novels are narratives of the interior, their success built on style and feeling rather than on plot, and I always doubted they would work on screen. But if later episodes are as good as the one based on Never Mind (the first novel), the much-hyped Patrick Melrose can be said to be a great success, if not exactly a complete triumph.

In a special edition of The Windsors (9pm, 15 May) Harry and Meghan took Charles to LA to meet her mum, and Pippa fed Kate doughnut smoothies the better to make her bum too big for her matron of honour’s dress. An hour is probably too long to spend laughing at Beatrice and Eugenie’s Sloane up-speak and the total inability of William to pronounce any word correctly. Still, Bert Tyler-Moore and George Jeffrie’s show had its moments. Chief among them was the one when Harry ran through the pals – not only poor Rupes, Jono, and Grunter, but also Spunky, Nobbles, Shagmonster, and Sir Vomalot – who wouldn’t be attending his Meghan-prescribed stag night to a health spa and a Ted talk on the Power of Yes.

Patrick Melrose (Sky Atlantic); The Windsors (Channel 4)