With its look at the effect of Aids on the gay community, an aggressive homophobe turning out to be gay, its deft balancing of comedy and tragedy and its brief detours into heaven, Jonathan Harvey's Canary is very much his Angels in America. It's a lot shorter - just over two hours compared to Angels' seven - and occasionally it tries to cram too much in to its comparatively brief running time, but it's still a very compelling work which manages, on a number of occasions, to be incredibly moving.

The focus for this examination of 50 years of gay history is Tom (Philip Voss), a Chief of Police whose home is under siege from the press when an out TV celebrity  Rusell (Sean Gallagher) reveals the secrets and lies on which Tom's based his career. His son Mickey (Ben Allen) didn't die in a traffic accident, but died of Aids. Even more scandalously, Tom once had a male lover who - in order to save his own skin - he testified against in court. His lover Billy (Kevin Trainor) escapes prison only by agreeing to undergo treatment, but it's treatment which is little short of torture - a form of aversion therapy involving lying in his own excrement for three days.

Jumping between the early 60s and the present day, the play highlights the injustices that were routinely meted out to those who chose to love members of their own sex. Early on Tom's father - himself a policeman - warns his son about the dangers of his disgrace by informing him of Alan Turing's fate. Turing, who despite having saved the lives of countless thousands by developing codebreaking technology which shortened the war, was chemically castrated because of his homosexuality. As Tom's father says, he later committed suicide by eating an apple injected with cyanide.

Others making an appearance include a double-entendre prone Mary Whitehouse, a heartless Margaret Thatcher who's not particularly bothered by the Aids crisis seeing those contracting the illness as having brought it upon themselves, and an almost heroic Norman Fowler trying to steer the Iron Lady into doing the decent thing (even though he finds it hard to properly enunciate the word "vagina").

In one particularly inspired scene, the theatre is turned into a 1971 meeting of Mary Whitehouse's Festival of Light. Mrs W expresses her concern over Cliff Richard's fear of "the advancing finger of homosexuality" and finds herself agreeing with a banner expressing that the singer would make a very good royal: "Cliff Richard for Queen". We then see the Gay Liberation Front turning up in drag, releasing mice, sounding horns, and generally acting the giddy goat.

The play isn't just a history lesson. It adroitly handles the pain of its characters - even when it's self-inflicted. A number of the scenes involving Tom trying to atone for his past treachery by comforting his dying son, and his wife (Paula Wilcox) asking forgiveness from her dead son had me in tears despite trying with every ounce of my willpower to resist.

Only one scene rings false. Russell picks up a young man who is written - fairly clumsily - as the embodiment of the bad, selfish, hedonistic homosexual. The lad's a "bug chaser", believes people with HIV are "losers", thinks the disease is "so last century" and besides even if he contracts it he'll "just take a few pills". But it's a minor misstep in a play that's thoroughly entertaining, moving, beautifully directed and acted.

Canary is at the Theatre Royal until Saturday

For more information and to book tickets click here.