First Night: Statement Of Regret, Cottesloe Theatre, London

This latest work by the award-winning playwright Kwame Kwei-Armah has a wilder, funnier, more dangerous and ultimately more tragic piece struggling to get out – but it's caught by the ankle in the trap of a 1970s debate-style drama.

The scenario that would benefit by being treated with a free-wheeling ferocity focuses on the co-founder of a Black Policy think-tank and shows how – under multiple pressures deriving from guilt over a recently deceased West Indian father and conflicted emotions over his two sons (one legitimate, one not) – he succumbs to the bottle and to mental crack-up. He turns into an outrageous loose cannon, spouting to the media his view that money should be paid in reparation for slavery only to blacks of West Indian descent. So anti-African does he become that the BNP and UKIP farcically start to woo him. Like Hamlet crossed with Lear, he listens to the promptings of a revenant father and winds up an old, lonely mess of madness-cum-sanity.

What this material needs is the reckless, searching, no-holds-barred talents of a Patrick Marber in his Howard Katz and Don Juan in Soho mode. Instead, for the most part, Kwei-Armah deploys the spell-it-all-out, tidy-minded methods of a David Edgar.

Premiered in a production of woefully stiff staginess by Jeremy Herrin, Statement of Regret is located throughout in the offices of the think-tank where, after a break, Don Warrington's Kwaku Mackenzie returns to find that there has been an ideological shift among his staff. The think-tank may have been instrumental in the creation of a new Ministry of Race but now "the [smart] money is in self-criticism" – research, say, into varying educational achievement levels within the black community rather than the struggle for reparation.

The play raises important issues. The think-tank is a classic case of an institution striving to preserve itself at the expense of reneging on its original principles. The hostility between the two sons encapsulates a larger conflict arguably played out as part of a white-dictated game. Does the buck never stop?

The trouble, though, is the presentation. There's a leaden, creaky explicitness to the writing and the production. Nothing is oblique, or free enough to take itself by surprise.

You know that this will be the case from the moment that the new intern (not yet disclosed as the illegitimate son) enters and begins volubly contradicting his bosses and brandishing his credentials as a First-Class Oxbridge graduate and a PhD expert on "post-traumatic slave syndrome". It's the kind of production where characters are mechanically dragged to centre stage when they are delivering a "big point".

The office has an in-house eccentric, a kind of Wise Fool figure who is significantly given an insufficient airing. Struck by Kwaku for making a humane intervention, he cries: "I can't take it ... I can't take it." He's not the only one.