Sinead Matthews tells Bridget Galton how ‘thorough professional’ Mike Leigh is a pleasure to work with.

AS Margaret Thatcher’s Tory government swept to power, director Mike Leigh staged a compassionate, caustic and intense slice of contemporary working class life at Hampstead Theatre.

Set in a Kilburn High Road bedsit, the highly naturalistic Ecstasy doesn’t reference the political upheaval of 1979, but its undercurrents of devastation and despair nevertheless reflect a society on a precipice.

Leigh of course has gone on to have a distinguished film career.

Now for the first time he revives an old play – at the theatre where it was first performed.

Among the cast is Crouch End actress Sinead Matthews, who has previously worked with Leigh on award-winning films Vera Drake and Happy-Go-Lucky.

He cast her straight out of RADA to play an expectant mother who goes to Vera for an abortion.

“It was really amazing, that was my first job. It was a very pure experience. Mike is a complete and thorough professional, very caring of his actors and Imelda Staunton was a joy to work with. Considering what the film was about we had a great laugh. I felt spoilt really.”

In Ecstasy, Matthews plays the perky, garrulous Dawn, a Brummie who has lived in London for a decade and is unhappily married to uncouth Irishman Mick.

Her best friend Jean lives in a shabby bedsit and has a boyfriend, Roy, who has forgotten to tell her he’s married.

Into the mix comes Roy’s angry wife and Len, an old friend from the past.

There’s an explosion of sexual violence and an undertow of forlorn vulnerability as Len, Dawn, Mick and Jean get drunk, smoke, sing, and grow sentimental in the tiny flat.

Matthews says the odd line has been ditched during rehearsals, but Leigh is otherwise sticking closely to the original script – “down to the punctuation”.

“Mike is very strict about each character. Each part is written in their specific accent and because of that the play has its own rhythm.”

Coventry-born Matthews read the play while studying A levels and fell in love with it.

“It was so sad and funny and simple, I thought it was a little masterpiece. It had these real people in it and was written with such strong individual voices.

“It deals with poverty, working class life and the loneliness of four people who are outsiders to London. They come together in this huge city. They are na�ve about living in a multicultural city, which comes through in their ignorance and fear about people from other countries.”

Matthews is by now familiar with Leigh’s legendary working style. He asks actors to present him with a list of people they know, and together they choose the best model for this specific character.

“You start with a real person then use them as a platform or a springboard to create a whole new character,” says Matthews, who went shopping and socialised with her Happy-Go-Lucky screen friends, in character, to develop the role.

“You spend three weeks creating a fictional back story of their lives so by the end you know where they met each other, how they walk and dress.”

To thrash out a script, Leigh then asks the actors to improvise around certain themes, getting them to come to rehearsal wearing clothes their character might wear.

In the case of Ecstasy, the script was already there, but Matthews finds the process “incredibly helpful”.

“What you wear affects how you walk upstairs and go to the toilet. Dawn is all tight-fitting sexy, feminine clothes, although she’s very hard and has been tough from an early age.”

She adds: “Doing one of Mike’s films, the actors create the shots – he lets you do the scene and works around you to put the camera where it will catch what you are doing. In other films you turn up, the camera is set up and you have to meet your mark.”

“Working with Mike every day for six weeks has been fantastic. His insight into the world of the play, into how people behave is incredible. He can give you one note and it can make you think about the character in a whole new light.”

She also praises Leigh’s insistence that actors separate from their character, referring to them by name rather than in the first person.

“It makes sense. If you are playing someone really troubled you can end up feeling crazy yourself. That detachment is a great discipline I have taken onto other jobs.”

Those include an acclaimed run at the Young Vic in November as Laura in The Glass Menagerie, playing a killer in TV drama Trial and Retribution, and a new play at the National Theatre Our Class.

But growing up shy, with a stammer, Matthews never thought she would make it onto a stage.

“I was completely obsessed with films growing up and used to dream about being an actress, but from the age of seven I had quite a strong stammer so I didn’t think it was possible. My parents gave me a self belief that I could do it. I went to drama school, worked on the stammer with speech therapy, got an agent and haven’t looked back.”

o Ecstasy runs at Hampstead Theatre until April 9.