It may be firmly rooted in South Boston, but David Lindsay-Abaire’s searingly funny dig at the uneasy co-existence of rich and poor in our cities could easily apply to Kilburn (see Zadie Smith’s NW).

NW actress Imelda Staunton is on pitch perfect form as earthy, humorous blue collar Margie, so desperate to support her special needs daughter she taps up an ex-boyfriend for a job.

While she’s on her uppers, he’s made good, fled the projects and become a doctor.

In another superlative performance of Jonathan Kent’s taut and compact production, Lloyd Owen’s Mike is a study in hidden anger and chippy unease at Margie’s intrusion into his office and home.

When he tells hard-grafting single parent Margie that anyone who works at it can transcend their surroundings, she’s stung to reply that you also need luck; in his case brains and supportive parents.

Shaky marriage

She also flings 30-year-old mud which rocks his already shaky marriage to Angel Coulby’s sympathetic Kate and exposes his inability to reconcile his past.

Lindsay-Abaire’s sharp ear for the awkward humour of the class clash crackles with energy; Margie mocks Mike’s self-satisfied definition of his luxury surroundings as ‘comfortable’ and when asked, ‘How’s the wine?’ flashes back, ‘How the fuck should I know’.

But this deeply humane play also evokes the precarious reality of the low-waged, where making rent or destitution turn on a cracked tooth, a late babysitter or a bingo win.

Ultimately it asks what it is to be a good person. You might think it’s easier if you’ve got a lot of money, but Mike turns out to have a steeliness that helped him leave and, in a twist on that American tale of self-sacrifice Stella Dallas, heartbreakingly proud and resilient Margie, shows a heroic selflessness in letting him go.

*****

Until April 5.