Frank and Percy review: Ian McKellen holds the audience under his spell in charming gay romcom

With a glut of roles from Hamlet to Gandalf behind him, 84-year-old Ian McKellen has absolutely nothing left to prove. He’s clearly on stage for the pure joy of it, and that sense of delight shines through in mischievous gay romcom Frank and Percy, where he and Roger Allam have a ball, playing friends-turned-lovers. McKellen pulls on a tiny rainbow-coloured tutu, strikes mock-alluring poses to disco anthems, and has the audience in fits with knowing comments about a “dextrous tongue” that’s schooled in saucier purposes than Shakespearean couplets.

Writer Ben Weatherill’s wry comedy is a precision-tooled vehicle for McKellen and Allam’s talents, one that’s motoring into London after a hit premiere at Theatre Royal Windsor in June.

It starts out in mundane territory. Against the grey skies of Hampstead Heath, confidently gay, confidently everything sociologist Percy (McKellen) and outwardly straight, recently bereaved retired teacher Frank (Allam) are watching their dogs play (in a witty touch, speakers that emit woofs and barks are hidden amongst the audience). Their conversation is colourless, at first. They talk about ways to die: the horrors of lonely heart attacks, and creeping pneumonia. Then Percy interjects: “deep-throating a cucumber?” His sudden outbreak of naughtiness sets the tone for what follows. Frank is the straight man here in both senses, a foil for Percy’s flamboyant wit, and a novice in the world of gay dating that he’s oh-so-gently introduced to.

The humour here has a real 20^th-century Englishness to it: its author Weatherill might only be in his early thirties, but it feels like he trained in the school of last-century greats such as telly comedian Victoria Wood and playwright Alan Ayckbourn. His play is laced with localised details – Pontefract cakes, spam fritters, the joys of finding wellies on the TK Maxx clearance rack – that are deployed to provide a touchingly ordinary contrast with its darker themes of ageing, isolation and corrosive pride.

Sometimes, that means things feel a bit formulaic. Sean Mathias’ production has a slow-moving, airless feel in the first act, with blasts of familiar-feeling classical music between scenes, and Morgan Large’s unnecessarily cumbersome revolving wooden set doing little to set a breeze going. But after the interval, things begin to sing. Frank and Percy go to Pride, and try both poppers and each others patience with erupting bursts of anger. Weatherill’s writing assumes a new poignancy, too. “I love champagne. Every time you sip it, it feels like you’re sipping from other celebrations,” says Percy, capturing the way that memories layer over each other as you get older, the past always present.

McKellen delivers these one-liners with a wonderfully arch flourish, letting them hang in the air like rings of smoke from a pipe. By his side, Allam’s more naturalistic performance has a compelling solidity, his face just barely showing alternate ripples of frustration and fascination with his charismatic dog-walking partner as they try to make their relationship work, beyond the Heath.

You can feel the whole audience gasp in relief when the pair finally grip each other in the kind of warm, passionate snog you rarely see on stage at all, let alone between two older men. It feels like a victory against loneliness, for the LGBT+ rights McKellen has spent his life fighting for – and, most of all, for this veteran actor’s love of holding a live audience under his spell.

The Other Palace, until 17 December