Charlotte Keatley's My Mother Said I Never Should is a play about women: the programme proudly proclaims that this is the first all-female show staged at St. James Theatre, Beyoncé’s Girls plays before the performance starts. And it is, and then some; it felt like being let into the girls locker room.

Keatley’s landmark 1987 play follows four generations of the Metcalfe family from World War 2 through to the 80s. Daughters disappoint mothers and mothers resent daughters against the backdrop of war, feminism and the arrival of Walkmans.

What cuts through the first act is coldness. Miscommunication plagues this family like a Mother’s Day from hell. That gives way to warmth in the second act, though there are some dodgy death dream sequences to endure first.

It would have benefitted from a more even distribution, and a shorter running time (it’s three hours including the interval). Director Paul Robinson could easily have skipped scenes and got to Keatley's point more swiftly.

At least the first act’s coldness is offset by frequent laughs. Keatley’s script plays on suburban paranoia and sex jokes with a heavily reliance on generation gaps. Lipman gets all the best lines of course – or she makes her lines the best. She's an expert at letting a line hang just so, and then dropping a bomb.

It's thrilling to see Lipman jump through decades; at once a distant mother, then an affectionate grandmother. In one of the play's best scenes, she's a young woman, just engaged, trying (and failing) to impress an off-screen mother.

But there’s no getting away from the bleakness. In a play where relationships are so strained – and the play loves to strain them – the most memorable and original scenes come when those relationships are relaxed.

It’s when Lipman and her great-grand daughter chat like schoolgirls, or roles are reversed and daughters look after their mothers that Keatley’s script shines. That flexibility allows the performances to breathe a little and it's a pleasure to watch.

The staging is tight – it's rather bleak but there is some inspired staging of crying babies. The set (stacks of televisions and an immovable piano) is brilliant at conveying not only changing time periods but also the constancy within that change.

A pace issue threatens to unravel that hard work – the question of illegitimacy is held off and off until it’s there and then the play is over. A little patience – a mother’s know-how – might have helped to mature Keatley’s script.

But when the performances are this good, and the closing tears so well earned, it’s easily forgiven.