If your condescending shrink knocks off your ex wife and raises your son, and your hunky but mercenary boyfriend shags around in the AIDS era, it’s no wonder you sing plaintively your life is falling apart.

In 37 songs for two and three-quarter hours.

As a character, Marvin at the centre of Falsettos is no catch – he has patrician have-my-dinner-ready expectations of his wife and his gay partner, and can’t find ways to bond with his son. In the skinny-jeaned clone-moustached gay 1980s in NYC, he’s dull and balding and bearded.

Both the subject matter and the music by William Finn and Sondheim’s serial collaborator James Lapine remain rooted their 80s and 90s settings – this is three one-act musicals stitched together into an over-long song cycle that’s a bit Torch Song Trilogy at the beginning, although missing the leavening humour of an overbearing Jewish Mother, and possibly The Inheritance: The Musical towards the end.

Director Tara Overfield Wilkinson and producer Selladoor overcome this with casting that is far more endearing than the characters: in particular Daniel Boys’ easy, warm voice makes you much more sympathetic to Marvin, and the ever reliable Laura Pitt-Pulford who makes a tour-de-force of wife Trina’s ‘I’m Breaking Down’ with heavily symbolic bananas meeting kitchen knives about the time Mrs Lorena Bobbit had the same idea

As with Evita, you could argue the through-sung/song cycle thing is an 80s/90s theatrical fetish we could now abandon, Falsettos would work far better with a crisp script peppered with authentic New York Jewish one-liners – get Bad JewsJoshua Harmon on board – than trying to cram everything into overly similar songs.

Two larky, poorly-choreographed productions numbers need the snip, too.

Despite its structural flaws all the performances are fine, so Falsettos proves genuinely touching.

Oliver Savile‘s well-observed initially arrogant Whizzer character mellows, and the bonding in the second act of the extended pretend-family in the generation before such things could be formalised, and in the earliest frightening days of the AIDS epidemic, is both nostalgic and tender.

until 23 November