PRESSING contemporary themes are addressed by an impressive, well-drilled cast in Chris Thompson’s Of Kith and Kin at the Bush.

Daniel and Oliver — played with emotional truth by James Lance and Joshua Silver — are a married couple expecting a baby. Their surrogate is close friend Priya (the glowing Chetna Pandya) who, it turns out, is using two eggs from an anonymous donor, with one fertilised in vitro by Daniel and one by Oliver.

Only one of the two embryos has been implanted but we don’t know which and it's unclear which of the two men is the biological father.

It’s complicated — and a fertile plain for the dispute that erupts when Priya suddenly and unexpectedly changes tack and refuses to play ball.

Thanks to Robert Hastie’s expert direction and James Perkins’s simple but beautifully judged design, it’s a vivid and engrossing production.

Scene changes are executed with military precision and we’re riveted by the twists and turns of the narrative and the multiplicity of questions that emerge. It’s fascinating, if only to see what will happen next as the play leads us through uncharted territory.

Somehow, though, while we embark on the journey, we never quite arrive. All angry outbursts are the same in pitch and register. And the questions come thick and fast.

In complex families, built on selected as well as biological bonds, what does kinship mean? How easy is it for older gay men to conform to the conventions of marriage after a sex life immersed in fear, danger and subterfuge? What is the emotional impact of surrogacy on all concerned? How easily can ageing relatives from simple backgrounds adjust to the new realities of same-sex parenthood?

And how easy is it for partners — gay or straight — to be open and honest with each other at all times?

These and more puzzlers emerge but are left hanging in a work that never really rises above debate, despite the valiant efforts of the cast to flesh out the characters.

We’re never really moved because the script relies on diatribe and not on perspicacity. Thus the courtroom, the magistrate, the woman in imminent labour and the baby himself never quite ring true, though Donna Berlin’s wise, wry magistrate and Joanna Bacon’s seamless transition from Daniel’s humdrum mum to acid family lawyer entertain.

A stimulating evening and the questions raised are of urgent current import. But, in the end, the play’s characterisation and denouement feel half-baked.  

Runs until November 25, box office: bushtheatre.co.uk