Some of the most heart-stopping moments in the Elton John biopic Rocketman, the stratospheric hit which made a Golden Globe-winning star of Welsh actor Taron Egerton (of Kingsman renown too), are those in which the troubled prodigy expresses sexual confusion and faces the prospect of personal and professional rejection for coming out as gay.

Terrific at conveying hurt, yearning and simmering self-doubt, Egerton now stars in Marianne Elliott’s revival of Mike Bartlett’s 2009 play Cock, a piece smartly and tragicomically about ongoing confusions of sexuality, the suffocating restrictions of categorisation and the agonies of the heart.

The puzzling thing is, though, that Egerton, who has trod the boards a few times before, isn’t taking the lead of John, a man who, having lived a gay life with a longstanding partner, suddenly falls for an interested woman and is torn between worlds, yet wonders why he has to choose.

The role of the protractedly, and perturbedly, unsure anti-hero in fact falls to Jonathan Bailey, who has become a face to watch in Bridgerton, eminently so in the imminent new season. Egerton has been cast instead as the unnamed M, the partner in question, and de facto rival to that unexpected siren, W (Jade Anouka, recently seen in His Dark Materials).

To some extent, Bailey’s centre-stage prominence makes sense. He got an Olivier award for his part in Elliott’s dazzling revival of Sondheim’s Company, delivering a sexuality-flipped rendition of the pre-marital panic-stations showstopper Getting Married Today. Openly gay, the actor is neatly assured at suggesting a confident, charismatic man about town whose ease in his own skin succumbs to prickly disquiet.