One of the challenges of staging a piece of verbatim theatre is to charge the testimonies with just the right level of dramatic action so as not to dilute their integrity or prevent them from turning into a series of talking heads. A challenge which Paula McFetridge, artistic director of the Belfast-based Kabosh theatre company, for the most part succeeds in navigating with nothing but an imaginary line, two chairs and ethereal projections by video artist Conan McIvor.

Though the lack of movement in the opening scenes is a deliberate embodiment of the wary standoff between Constable McCabe (Vincent Higgins) and Garda O’Halloran (James Doran) who patrol opposite sides of the Irish border; and a stark contrast to the easing of tensions when after two decades of radio contact they eventually cross the divide to shake one another by the hand.

With Brexit having re-politicised the Irish border, escalating tensions and threatening a return to hostilities, writer Laurence McKeown, who turned to academia and the arts after a period of incarceration as a political prisoner, knows only too well that though the action of Green & Blue is rooted in the past, its message of hope is seriously under threat.

If such an outcome is to be avoided, then the lessons learned by the likes of McCabe and O’Halloran – that there is more that unites us than divides – will be instrumental in ensuring peace. After all, they lived at a time when brothers in arms became “brothers at arms length”. And some of their forefathers were faced with the unenviable prospect of aiming a rifle at a uniform they once wore.

As you can imagine, gallows humor and (as RUC officers were instructed) a “pleasant, but formal” attitude are prerequisites for survival. And both are in bountiful supply in McKeown’s intelligent script and Higgins and Doran’s strong performances. One scene in particular making a comedy out of a crisis when reports of a stray dog killing sheep is comically misinterpreted as “Mad Dog” Adair on a killing spree.

Though it is the level of detail, humanisation of the Troubles and difficulties faced by those in uniform which linger long in the mind after the well-received curtain call. “Could I kill?” ponders one of the officers at the start of their career. To which he replies, numbly, “It helps if I can’t see them, if they’re just figures in the dark, out there, not real.”

Peter Callaghan