When Kwaku Mackenzie, the head of a black think-tank, goes on live television and drunkenly declares that it’s high time black people were more racist, all hell breaks out back at the office.

Statement of Regret - Kwame Kwei-Armah’s new play in the Cottesloe, his third for the National about tensions and identity crises in the British Afro-Caribbean community - is a fascinating document based on current thinking about “post-traumatic slave syndrome” and reparations for past wrong-doing. As drama, though, it leaves quite a bit to be desired.

The novelty of seeing an office play populated by black men in suits was only matched by the novelty of spotting a similar constituency in the first night audience. Kwei-Armah is obviously voicing some very potent misgivings about new black politics. And the core is Kwaku’s insistence on creating further divisions between the West Indian and African immigrant factions.

The same theme underpins Roy Williams’ energetic new play Joe Guy at the Soho Theatre. But whereas Williams lets his drama do the talking, Kwei-Armah wants his talking to do the drama. And for that to work, I imagine you have to be directly involved in his subject.

Jeremy Herrin’s production – an NT debut for the Live Theatre, Newcastle, associate and director of Polly Stenham’s blistering That Face in the Royal Court Upstairs earlier this year – gives the dialogue every possible chance and boasts a superb cast of black theatre veterans, from Don Warrington’s craggily disintegrating Kwaku, haunted by the cheery ghost of Oscar James as his dead father, right through to Trevor Laird as an office eccentric dressed in native black Indian garb and super-smooth Colin McFarlane as his increasingly frustrated right-hand man.

The flash point of the argument comes in the play’s best scene between Kwaku’s two sons, who represent either side of an ideological divide. Javone Prince is the impassioned inheritor of his dad’s blinkered principles while Clifford Samuel as his Oxford-educated step-brother, and the new office intern, sees room for adjustment and even trimming.

Other fixtures in Mike Britton’s gleaming, split-level office design include Angel Coulby as the secretary with whom Kwaku is having an affair and Chu Omambala as the gay brother who raises such tricky black-on-black subjects as wife-beating and homophobia. Needless to say, Kwaku’s wife Lola (the magnificent Ellen Thomas) is not a happy bunny and makes a big deal of first leaving, then coming back, slamming the door like Ethel Merman ready to lay down a big number.

- Michael Coveney