Willy Russell’s Educating Rita is perhaps his finest comedy, but his Shirley Valentine (put up at the MADC Clubrooms, St Venera) punches even harder, if this long monologue in two acts is performed as well as Isabel Warrington performs it in Michael Mangion’s very subtle production.

This is a comedy that is amusing, but also very moving at times and kept me gripped all the way.

Shirley Bradshaw, née Valentine, is a 45-year-old housewife living in a small house in Liverpool. She has lost any zest she may have had for life and realises, with some fear, that her increasingly unsuccessful married life has prevented her from enjoying the gamut of experiences that life offers those who open themselves up to them.

She has long lost the ability to be the lively and feisty person she was before marriage and though her husband Joe says he loves her, he no longer behaves as if he does.

The sex she has with him is unexciting and she realises the reason why after getting to know that she has only been made to experience one type of orgasm. Her son and daughter, both young adults, do not exactly shower their affection on her and have both left home.

Shirley does not seem to have many friends and spends much time in her kitchen talking to the wall and pouring out her despondency. She has, however, one possibility of getting out of the existential rut she is inhabiting: Jane, who is her only close friend, has won two tickets for a holiday on a Greek island and has offered one to Shirley.

While Shirley would dearly love to go, she is terrified by the furious reactions of Joe if she were to tell him he will have to prepare his meals and do the washing for the fortnight she is going to be away. She finally finds the courage to go on the trip when Joe, a man of habit who was expecting a meat dish, throws the plate of egg and chips she has cooked (apparently her stock dish) into Shirley’s lap.

Comic timing, of course, has always come naturally to this actress

In the second act, which is shorter, Shirley is on the Greek island. Though Jane has immediately found a man to have sex with, leaving Shirley on her own, Shirley is enjoying herself quietly. Until she realises that life is now due to give her some exciting experience, and this she finds with Costas, a waiter in a taverna, who takes her round the island on a boat and with whom she swims in the buff and finally has the kind of exciting sex she has always lacked. In Shirley’s words, he has “led her to Mount Clitoris”.

I shall not reveal the play’s ending except to say it is a happy, but open, ending.

Russell’s script is finely constructed with a variety of mood changes and an abundance of witty and comic lines. I wish I had noted down a few of them, and can only relay one funny line from Act Two.

Here, Shirley relates how she had to put up with the company of fellow Britons with poor and provincial tastes in food. She ends up commenting that, had they been at the Last Supper, they would have asked for a plate of chips.

My only serious objection to the script relates to the longish and quite hilarious account by Shirley of a school nativity play in which her young son, playing St Joseph, innocently scuppers the simple tale of Christ’s birth. The episode is fine in its own right, but not greatly relevant to Shirley’s outpourings about her sad life.

The script, with its picture of a very despondent woman who finds the guts to turn her life round when common sense tempts her to do nothing of the sort, is a gift to the performer, a gift Warrington and Mangion seize gratefully.

Warrington plays at the height of her powers, both as a comic and dramatic actress. In the small and deliciously intimate MADC theatre, with its low stage, her stage persona grows and grows until her every emotion and her every experience keeps the viewer in thrall.

If her provincial accent is sometimes inconsistent, if, when she comes dressed up towards the end of Act One she looks too much like a well-dressed woman used to this kind of attire, this does not prevent the overall portrait of a woman finally on the way to finding her old and real self.

She relinquishes Shirley Brad-shaw and becomes Shirley Valentine once more, achieving the basic, strong consistency of a character who comes to real life on the stage.

Her technique is admirable, seen at its surest in the subtle transitions she makes from the wry and comic to sadness. Her playing is particularly impressive in the scene where she says how, after many years of leaving school, she meets a former classmate whom she envied and used to speak nastily about.

This meeting happens in somewhat humiliating circum-stances. When Shirley describes how this woman treated her with remarkable kindness and affection, telling her how much she admired her, Shirley begins to weep as she rediscovers the soft emotions of loving and caring.

Warrington’s pauses and use of soft tones at the climax of this scene make us realise that this meeting may have been crucial in bringing about the change Shirley so desperately needs in herself and in her life.

Comic timing, of course, has always come naturally to this actress who also shows a mastery of different voices for the people she has met. I have little doubt that this will be one of the finest performances on the Maltese stage during 2014.

Shirley Valentine receives a last performance tonight. The house, I hope, will be packed.