Manor review – an excellently performed but metaphorically overstuffed drama

Moira Buffini's new play begins like a locked house murder mystery: a dark and stormy night, a squabbling couple, a man dead from a fall down the stairs, a group of ill-matched strangers seeking refuge and unable to leave.

Among the refugees, escaping the terrible flood which is engulfing the land, and threatening the ancestral manor with its rising waters, are Ted, the charismatic leader of a far-right group (Shaun Evans, best known as the young Endeavour Morse), his blind girlfriend Ruth (Amy Forrest), an accident and emergency nurse called Ripley (Michele Austin) and her clever, sulky daughter Dora (Shaniqua Okwok), who are on a weekend break from Balham and a liberal, gay vicar (David Hargreaves). There's also Perry, a disaffected and lonely lad who lives on the land and Anton (Peter Bray), an equally disaffected and lost follower of Ted's.

Lady Diana (Nancy Carroll) provides blankets and grudging hospitality, while simultaneously comforting her own daughter Isis (Liadán Dunlea) and wondering what to do with the body of her husband (Owen McDonnell), a drunken one-hit wonder whom she actually pushed down the stairs in the middle of a fight.

As one might expect tensions rise and arguments break out. Sometimes, the clashes that arise are darkly funny and sometimes sinister. But the problem with Buffini's play, directed by her sister Fiona, is that it is so weighted down with state of the nation ideas and metaphorical notions – clue, Ted's fascist organisation is called Albion, the manor is built on the site of the civil war and is called Burnt Marple, that it never quite takes off.

After its brilliant set-up, it always feels as if it is straining towards its purpose, with its characters as symbols rather than as real, rooted human beings whose actions will let its points unfold more naturally. It's not helped by being staged in the wide-open spaces of the Lyttelton where, particularly from the back of the stage, some of the actors have to over-emphasise simply to be heard.

Lez Brotherston has provided a stunning set, dominated by a steep staircase, both ruin and stately home, with tracery windows and mantelpiece set slightly askew and suits of armour lurking by the door. As lit by John Clark, with Nina Dunn's video projections suggesting the constantly racing sky, overcast with heavy clouds, it adds a sense of foreboding to the entire affair.

The entire play pivots on a sense of us and them, and who belongs in each camp, what that means in terms of British history – but also how it is defined by who people decide to ally themselves with. The best of Buffini's writing cleverly lays bare the roots of Ted's appeal: he has a seductive power (literally in Lady Diana's case), and an ability to make people feel valued, to sell them a sense of their own potential. It is Ruth who reveals its naked cynicism. "Truth," she says "is the argument that wins."

The play is also good on the intersectionality of right-wing politics, the way that one stance leads to another, so that misogyny and racism are tied up with climate change denial, and that all spring from selfishness, from a desire to cling to what you have. There's a gleam in Ted's eye when he imagines spending his £5 million fighting-fund on restoring the manor. Against him, stand Ripley's impassioned plea for a culture of sharing and the social and personal bravery she sees every day, and the vicar's belief in the transformative power of love.

It's all a bit schematic, but it contains some excellent performances, most notably from Carroll who reveals the vulnerability beneath her aristocratic mien, from Evans who has the stillness of a lizard waiting to pounce on its prey, and from Okwok whose belief in the future is nearly undone by Ted's ability to lie without shame.