With its two central roles, performed here by Felicity Kendal and Maureen Lipman, you might assume that the title of the late Peter Shaffer’s 1987 gentle comedy doubles as the names of his protagonists. Think of Rosemary & Thyme, the TV detective series in which Kendal played crime-busing plant pathologist Rosemary opposite Pam Ferris’s Laura Thyme. But no. Opposite Kendal’s bohemian tour guide Letitia Douffet, Lipman plays the emotionally repressed Lotte Schoen, hirer and firer at an English Heritage-style organisation called the Preservation Trust.

Lettice’s job is to regale visitors to a Wiltshire mansion with its history. But the history is deadly dull so she embellishes it with made-up details, such as how Elizabeth I nearly fell to her death on the otherwise unremarkable staircase. It’s Lotte’s job to sack her.

Director Trevor Nunn could not have chosen two more complementary comedy actors. These National Treasures play off each other like musical instruments performing the same tune but in contrasting tones: Kendal’s florid and fruity Lettice is prone to melodrama on a biblical scale while Lipman’s Lotte, whose father, we learn, was an Austrian-born refugee, is all clipped, icy efficiency. And it’s the melting of that ice that provides much of the play’s emotional core.

In a week where the country has been rocked by the heartrending events in Manchester, this is theatrical comfort food of the best kind. Shaffer, who died last year, wrote two female archetypes so well within the comfort zones of this production’s stars, one imagines they could swap roles without breaking sweat. The pleasure lies mostly in the familiarity of their comic acting chops, with Lipman’s brittle Lotte somewhat predictably revealing a heart of gold and Kendal’s actorly Lettice, somewhat unpredictably revealing that she’s actually a pretty good historian.

And yet there are moments where Shaffer’s writing displays surprising political currency. The most conspicuous of these happens in Act Three, for which the action moves to Lettice’s Earls Court bedsit (the transition from stately home, via Lotte’s Georgian office in London, to Lettice’s modest pad is terrifically realised by Robert Jones’s design). Lotte has arrived with a job offer for her former employee, and as the two forge a friendship under the influence of Lettice’s home-made Tudor hooch (made with the herb lovage) Lotte laments immigrants who import their extreme politics to this country. And suddenly the comfort zone is decidedly edgy.

It’s not a moment that lasts long or defines the play. The cause that binds these two is their hatred of modern architecture. But it does fleetingly chime with these violent and Brexit times.