There aren’t many clues in the programme or in the rather forgettable title of this play to give you an idea about what it’s all about – in fact I found myself referring to it in advance as simply “the Julie Walters play”, so if you too feel a bit of a blur as to its contents, I’m pleased to inform you, it’s a very engaging tale about an ageing “free-thinking” mother of the hippy generation, her two rather wayward children, the people who love them, the people who abuse their relationships with them, and how one’s passion for one’s cause can both help and hinder the world about you.

This is Stephen Beresford’s first play and he is admirably skilful at creating characters and writing funny but telling scenes. Despite financial strictures Judy hangs on to her ramshackled house to the obvious disapproval of wealthy neighbours. It’s a terrific, detailed set cleverly suggestive of one of those extraordinarily expensive Dorset Sandbanks properties – though the local references are all Plymouth-based – all art deco, garden and outhouses; but shabbily and carelessly furnished and maintained, with plenty of Indian Bhagwan ephemera, hippy bunting and a bottomless supply of alcohol. Judy’s obviously been a trying, difficult, brave, offensive and wonderful person all her life. Inspirational and exasperating in equal measure she steadfastly refuses to dumb down her vision for the sake of practicality. Her children Libby and Nick bear the scars of wayward upbringing and she still dominates their existence, even though they are now well entrenched in adulthood themselves. As the family work out their frustrations with each other over the last months of Judy’s life, Nick comes to the conclusion that they all have to accept they are individually responsible for their own “f***-ups” (his words), and this seems to me to be the main message of this very black and very funny comedy. The excellent set is matched with a well chosen soundtrack – in fact I loved the use of music in this production. Tracks from Judy’s finest hours, you imagine, work with empathy and irony to the on-stage action, and it was great to hear Peter Green’s plaintive guitar chords of “Oh Well” again. I’d forgotten how comfortably you are seated and what good sight lines you get in the Lyttelton stalls, and this production fills the imposing stage admirably.

The Lyttelton was packed; primarily I sensed, to see Julie Walters in action – and why wouldn’t you, she’s still a complete star turn. I last saw her on stage apparently performing oral sex on Richard Beckinsale in a hospital bed in Funny Peculiar at the Garrick in 1976, and she’s done awfully well since. Her Judy is a highly intelligent, fearless, erratic and slightly posh version of her creation Bo Beaumont, allegedly the actress who plays Mrs Overall. Julie Walters’ comic timing is immaculate but the role calls for much more than just comedy. She makes you believe Judy’s self-delusions. You share her loathing of the fascists. You are horrified at her deterioration of health and reliance on morphine. You are full of joy at her love for life. It’s perfect casting for this extraordinary character.

I also very much enjoyed Rory Kinnear’s performance as her son Nick; near destroyed through drug and drink addiction, you can tell he’s been a coward and a reprobate but his characterisation is so real that you warm to him instantly. His hapless attempts at chatting up young Daniel, whom the family allow to practice swimming in their pool, are very funny and his comic business with the can of lager was predictable but very believable. He too has impeccable comic timing, as you might expect from his parentage; and like Ms Walters, his performance reveals both the comedy and the horror of the character’s life and experiences.

As Judy’s clearly less-favoured daughter Libby, Helen McCrory makes sure all grounds are covered in her performance from her strict unsentimental dealings with her daughter Summer, her vacillating fondness for the three-timing Dr Peter, and her gooey appreciation of Daniel’s attention, to her every-emotion-under-the-sun relationship with Judy. She’s very convincing, and delivers her hard stark lines with great comic attack. It’s a cleverly written role, as the character develops from the person you think probably has the best grasp on reality to the person who arguably loses grip – and the things she loves – the most. It’s a very effective and hard-hitting performance.

In the smaller roles I thought Taron Egerton, in his first professional stage engagement, shows good promise as the awkward loner Daniel who blooms under Judy’s watch and carves out a positive life for himself. His testament, that it was because of Judy’s encouragement and support that he can now meet life’s challenges, was really movingly written and honestly played. Matthew Marsh as Peter looked the part and was suitably creepy and sneaky with his amorous attentions to both Judy and Libby, and his turning away from the family’s needs at the end of the play was unpleasantly disturbing. Isabella Laughland as Libby’s wounded and wounding daughter Summer breathed strong life into the Catherine Tate-style “difficult child” character, and I didn’t foresee the twist as to how Summer would develop, but it was very nicely played. She has a tendency to talk over the laughs of the previous line, though, which is annoying, as I missed the beginning of quite a few of her important speeches. She just needs the confidence to slow the pace down and simply wait.

There were one or two aspects of the story that didn’t quite hang true for me; receiving the cremated ashes in an urn on the same day as a funeral is extraordinarily quick work; and why would you arrange for a funeral to take place on the same day you have to move house, that seems to create pointlessly additional stress. Nevertheless it’s still a rattling good story with some fine performances, good characterisation and plenty to watch and admire on stage. Running in repertory until October and definitely worth catching.