It seems that at various times during her career Margot has advocated promiscuity then celibacy, childlessness then motherhood and so on. When challenged by Molly about her responsibility to the women like her who have changed their lives on the basis of her contradictory declarations, she replies, sounding like a radical Noël Coward, “My deargirl, I am not a life coach. I’m a provocateur.”

Margot has been handcuffed to her desk when her grown-up daughter Tess (Sophie Thompson) turns up. Tess, who has suffered from Margot’s titanic selfishness for years, is provoked to take the side of hostage-taker rather than hostage. The trio is eventually joined by Tess’s wimpish but loving banker husband and then by a virile young taxi driver who has been desperately trying to behave like a post-­feminist new man. All of them have bones to pick with Margot. However, in the eruptions that follow, Margot gives as good as she gets, as you might expect from someone famous for aphorisms such as “for every child born a great novel goes unwritten”.

Margot is a wonderful role for Eileen Atkins. She relishes every delicious mouthful but resists all temptation to overdo it, to turn monstrous Margot into a crude cartoon.

Unfortunately, under the direction of Roger Michell, some of the supporting cast do occasionally cross the line. There’s something over the top in the way that Anna Maxwell Martin’s Molly stoops her shoulders and clutches her hands. We already know she’s nervous and a bit bonkers: the twitchy physical manifestations sometimes look too much like acting. The same goes for Sophie Thompson’s Tess. She’s also been broken by Margot’s egotism and she too is hunched and clumsy, her voice alternating between a mousy squeak and an enraged bellow. That said, both Maxwell Martin and Thompson possess the timing needed for farce, and when both characters experience an unexpected erotic awakening it’s charming and funny.