The Orange Tree has a fine reputation for staging small-scale chamber musicals, from which some of the biggest names in the West End have launched their careers.

Director and composer Keith Strachan started out there and, this month, his son Matthew, who spent many childhood days in the old theatre above the pub, gets his own show, co-written with his novelist wife, Bernie Gaughan.

Next Door's Baby is Neighbours transposed to 1950s Dublin, only with songs and much better writing.

It tells the tale of two Dublin households, the O'Briens and the Hennessys, who are both entering their babies for the local rag's Bonnie Baby contest.

The drama arises from the question of to whom do little Connor and Max actually belong.

While the matriarchs - splendidly played as polar opposites by dowdy Louise Gold and glam Brenda Longman - do the mothering, the real mums struggle with secrets that neither Catholic morals nor neighbourhood reputation permit them to reveal.

Much of the joy of this piece comes from its rich Dublin humour. Strachan searched for hours through vocabulary books to find the best Irish insults and it shows, both in his quick, intelligent lyrics and Gaughan's sparky script.

Individual performances are terribly funny. Clare Louis Connolly in particular as the youngest O'Brien, a would-be primary school nun and Elinor Lawless is fabulous as Dymphna, who can get the perfect hair curl but is yet to bend her fiance to her will.

But what elevates the Orange Tree above a West End stage can also hamper. In such a small space, the singers have no need for amplification but some cast members over-sing so that, at times, the sound is rather strained.

It can also feel crowded, though perhaps director Paul Prescott wants to show how much these neighbours are living on top of each other.

But these complaints are to miss the point. Next Door's Baby is a warm, intelligent piece and the chamber form is perfect for highlighting the minutiae of Dublin life and the deeper emotional turmoil of growing up a teenage Catholic.

As such, the stand-out performance is by Riona O'Connor as Orla O'Brien, who grows in stature as her character emerges from behind the kitchen sink to become the heart of the story. A great voice, a great Irish accent and a great actress.