The Linden Tree is the latest example of the Orange Tree's splendid commitment to championing plays which have fallen out of the mainstream repertoire. Unfortunately, although Christopher Morahan's nicely balanced production is a creditable attempt to make the case for J.B. Priestley's 1947 state-of-the-nation play, it cannot disguise its weaknesses.

Its themes of idealism against materialism and tolerance against bigotry are of course still relevant today, but the characters tend to be merely mouthpieces for particular points of view. Sometimes it feels like we are in a debating society rather than a theatre.

The action focuses on a family reunion to celebrate Professor Robert Linden's 65th birthday at his home in the provincial university city of Burmanley. But the celebrations turn sour as divisions within the family are exposed. The Professor has no intention of retiring as he still believes he has a duty to carry on teaching his humanistic version of history to young people, but it seems the new Vice-Chancellor has other ideas – and so too do his wife and three adult children.

It becomes clear that the Linden family represents immediate post-war Britain. The Professor's enlightened belief in the importance of education in opening minds is set against the more pragmatic agenda of the 'educationalist' Vice-Chancellor. Mrs Linden's determination to persuade her husband to retire is backed – at least initially – by their son Rex, a rich playboy businessman (dodgy capitalism); daughter Jean, an emotionally repressed doctor (clinical science); and daughter Marion, a Catholic convert with her own family in France (moralizing religion). As each one argues their viewpoint, it seems that not just the future of their father but that of the country is at stake.

The play actually works better on the personal than the political level. There is a strong sense of the Professor not wanting to give up work as retirement is the downward slope towards death (backed up by the use of Elgar's elegiac Cello Concerto). The suggestion that the nation is also at a crisis point seems more contrived. As a socialist at the time of Britain's first majority Labour government, Priestley appears surprisingly pessimistic about this dawn of a new era. The drabness of post-war austerity (there is much talk of rationing coupons and the black market) casts its grey shadow over the play.

The Professor is given a wonderfully authoritative and sympathetic presence by Oliver Ford Davies, who conveys just the right mixture of stubbornness and idealism, while Anna Carteret makes Mrs Linden's rather dubious scheming understandable. Roger Barclay's Rex is charmingly frank about his pursuit of money and women, and Elizabeth Marmur and Hannah Yelland are the squabbling sisters Jean and Marion, giving voice to Priestley's post-war blues.

- Neil Dowden