It is 14 years since Neil Jordan had an enormous success with The Crying Game, in which one character’s ambiguous sexual identity put a sensational twist in the tale of terrorism, the British military and Northern Ireland. Now Jordan revives these tropes in this adaptation of Patrick McCabe’s 1998 picaresque novel Breakfast On Pluto - in which transvestism is a defiant rejection of bigotry, labels, and borders.

Cillian Murphy plays Patrick “Kitten” Brady, a drag queen with attitude from a small town in the Irish Republic, close to the border. He is the secret son of the local priest, played by Liam Neeson, who got his housekeeper pregnant and arranged for the resulting baby to be farmed out to an uncaring foster mother. Growing up in the 1960s and 1970s, Kitten scandalises everyone with his addiction to girls’ clothes and precocious sense of glamour. But Kitten is obsessed with the idea of his mother - who is supposed to have made a new life in London - and, all but penniless, he heads off to the English capital with a romantic notion of tracking her down.

We are presumably supposed to be cheering for Kitten, as a lovably exuberant rebel who makes joyless priests, cruel Brits and stone-faced Provos look silly with his antics. Actually the character is bafflingly charmless: narcissistic and unsympathetic, and the shrill, twittering monotony of Murphy’s performance becomes exasperating.

His story begins with a couple of CGI robins swooping over the rooftops, commenting on the action and establishing the uncertain, sub-magic-realist sense that Kitten’s self-narrated mythologising is at some level unserious. Yet Kitten appears to get involved in deadly serious situations: he experiences first-hand the casual arrogance of the British border patrol and the icy ruthlessness of the IRA. Turning tricks in London, he is nearly murdered by a kerb-crawler played by Bryan Ferry (a disconcerting piece of novelty casting) and even gets blown up in a pub bombing only then to be beaten up by the London police as a typical Paddy suspect. But all the time he airily waves away any suggestion that he should take any of this seriously: “Oh serious, serious, serious ... “ But isn’t it serious? Kitten actually flirts with a copper who just a few days previously had stood idly by while his colleague beat him up. His unending campness saves him from being half-killed on separate occasions by the Met and the Provos; it is miraculously disarming - the cross-dressing Christ in high-heels? - but it can only be disarming in this world tinged with black-comic fantasy.

Kitten’s refusal to conform to sexual stereotypes is an apolitical plague-on-both-your-houses gesture, and certainly an effective way of showing how the warring sides have something in common: nauseating macho arrogance. But having detached himself from the political contest, where are Kitten’s emotional commitments? His relationship with his mother, Eileen, has most power when it is yearning fantasy: when confronted with her in the flesh, Kitten becomes tongue-tied and it is all a bit of let-down - Eileen is played by Eva Birthistle, who recently gave such an excellent performance in Ken Loach’s Ae Fond Kiss. Kitten’s friendship with the pregnant Charlie (Ruth Negga) is also filtered through his incessant, brittle posturing.

Stephen Rea has a droll presence as a conjuror and hypnotist who becomes captivated with Kitten, using him as an assistant and mesmerising him into thinking his mother is in the audience, for the benefit of a heartless, chortling crowd. Yet Kitten’s hypnotised rapture doesn’t seem that much different from the real thing. The only person in the film who really comes to life is Brendan Gleeson, playing John-Joe, an itinerant Irish actor who briefly gets Kitten a job in a horrific Wombles theme park. As Great Uncle Bulgaria, John-Joe has a certain authority which is displayed when, in full costume, he punches the haughty English manager for accusing him unjustly of breaking a mallet. Kitten’s adventures rattle along divertingly enough, but it is difficult to make any emotional investment in a character who is interested chiefly in himself.