Matthew Macfadyen looks a little awkward. The 51-year-old actor is sitting on an extremely low-slung sofa in a studio in west London, his 6ft 3in frame bent into a sort of lotus position so that his knees nearly bang the floor. With his thatch of silvery hair, intense blue eyes and watchful manner, he looks like a beanpole guru; albeit a guru dressed in a bespoke three-piece suit by Anderson & Sheppard in a thin, chocolate-coloured wale.

He’s quite awkward in conversation also. Possibly because I am nervous too. Macfadyen is one of my favourite actors and I’m conscious that I’m coming on too powerfully, filling space with long pontifications about dramatic theory while he smiles politely and offers one-word replies. Does he think that the dramatic genre of things shrinking is a comment on US consumerism, for example. His eyebrows twitch upwards in a panic: “Probably..?”

That Macfadyen is tongue-tied in real life shouldn’t be surprising: actors are not required to be remotely like the characters they play. But it surprises me nonetheless because I associate him with such sharp, spiky, sparkly dialogue. Take his Mr Darcy, in Joe Wright’s Pride & Prejudice (2005), in which he woos Elizabeth Bennet with: “You have bewitched me body and soul. And I love… I love… I love you.” Arguably the sexiest pick-up line of all time. Or Tom Wambsgans, the Machiavellian sycophant married to Shiv Roy in HBO’s Succession, whose caustic put-downs – “buckle up, Fucklehead” – drop into conversation as breezily as exclamation points.