It is the start of May Sumbwanyambe’s uneasy drama and Joseph Knight (Omar Austin) is showing John Wedderburn (Matthew Pidgeon) the book he is reading. Seeing it is by Plato, Wedderburn comments on the Greek philosopher’s thoughts on fathers and sons. His interest seems to reflect on his own relationship with the younger man.
His level of affection is more than comradely, perhaps more than paternal. They stand close, like family members or even lovers. Their intimacy makes you wonder whether it accounts for Wedderburn’s sexual dysfunction with his exasperated wife, Margaret (Rachael-Rose McLaren).
But it is more complicated than that. Because this man talking chummily about fathers and sons is a slave owner. The younger man is his property. It lends a creepy power dynamic to the scene. However freely Knight may speak, however finely attired he may be in his silk stockings and gold-braid cuffs, he is not free.
And the sexual dysfunction, well, maybe that has something to do with Wedderburn’s 10 years in Jamaica where his appetite for human “bed warmers” was characterised by violence and humiliation. His colonial experiences in the Caribbean have so disturbed him that he has contracted Margaret never to mention Jamaica.
The corrupting impact of slavery extends to the housemaid Annie (Catriona Faint), whose status in this fraught household is lower than that of Knight, her future husband. Both Wedderburns are callous in their treatment of her.
Written economically in spare, fragile scenes, Enough of Him refuses to be celebratory, even though the historical Knight set a legal precedent in 1778 by persuading a court that slavery was not permissible under Scots law. Rather, it is fractious and troubled, a game of chess that cannot be won.
For the National Theatre of Scotland, director Orla O’Loughlin plays it like a slow square dance, the actors taking their time on a set dominated by Alexander Nasmyth’s view of Loch Katrine, a landscape where wilderness and civilisation collide. In Fred Meller’s design, the painting boils up into a volcanic red at moments of intensity, while Knight turns on Wedderburn to put him right: whether they both lost fathers or not, a master and slave can have nothing in common.
• Enough of Him is at Pitlochry festival theatre until 29 October. Then touring until 19 November.
