1987: We are in Thatcher’s Britain and it’s not pretty. The Eighties club scene is rampant, the coke’s snorted with gay abandon and in the toilets at Heaven Don is having his wicked way with all the pretty boys – ‘love everlasting, for one night only’. And so it is that Mozart and da Ponte have been purloined and radically transformed into a rather different entertainment, a Don Giovanni unlike any you might have seen before and, as might befit performances at London’s best-known gay club, role-reversal is the order of the night.

The idea, I understand, is to make Mozart relevant to a new, very different audience, far removed from the genteel opera house ‘elite’. Heaven, located Under The Arches at Charing Cross, is about as far removed as there is. The entertainment begins with words from Herself (as I recall, the lady was not for turning) and Giovanni is reinvented as Don, a debauched gay playboy and nightclub boss. Inspired by New York’s legendary Studio 54 and Matthew Bourne’s all-male Swan Lake, which latter I regret never witnessing, producer Richard Crichton has reversed the gender of all the roles except that of ‘Don’ himself. So Donna Anna becomes Alan (Patrick Ashcroft), a younger closeted man from a wealthy and privileged background, while Donna Elvira, much the most interesting of the women in the Mozart original, is turned into Eddie (Mark Cunningham), a middle-class out-of-the-closet gay man who works in the city. Naïve little Zerlina is transformed into dippy Zac (Mark Dugdale), a working-class boy from Milton Keynes, visiting London with his brand new fiancée Marina (Helen Winter, a big fiery improvement, I’d say, on boring old Masetto), who seems rather to enjoy the attentions of the wily old letch (‘You know that no means yes!’).

Meanwhile, the excruciatingly dull Don Ottavio becomes Olivia (Stephanie Edwards), in love with her best friend Alan despite his homosexuality – never the most engaging part of Mozart and da Ponte’s work and hardly more exciting here. The Commendatore becomes Alan’s imposing mother Petra (Tamsin Dalley), while Leporello becomes Don’s female PA Leo (Zoë Bonner), whose catalogue aria tells of Don’s numerous conquests on Clapham Common (507), Hampstead Heath (611) and in the toilets at Heaven (hundreds more) as well (rather lamely) as ‘in his bedroom, 1003’.

Crichton says Leporello’s aria was his original inspiration for this production, which, after six nights at Heaven, will have a run-out in June at WorldPride. ‘I had a  friend who had way more lovers than that,’ he says. ‘The penny finally dropped. Although the idea started as a bit of a joke, here was a story which actually reflected real life.’

So, what is one to make of it? It’s certainly not da Ponte, but David Collier’s witty lyrics (as blue, as you might expect, as Turnage’s Anna Nicole at the ROH last year) regularly had Heaven in stitches. It was described as ‘promenade opera’ which saves on the seating and jam-packs more people into a confined space – you turn off your mobile, keep shtum and are then meant to feel free to follow the actors around as they utilise all Heaven’s nooks and crannies.  Except that no one did. This audience might have been new to opera but they stood stiff to attention, as well behaved and respectful as Covent Garden’s finest (and no sniff of any Rusalka-esque booing!) So maybe not da Ponte, but the 10-strong chamber orchestra, playing with a degree of panache for Colin Pettet, made sure that there was plenty of authentic Mozart on show. Actually, Mozart knew what he was doing and changing round the voices interferes with the Mozartian balance, but if you take this for what it is it works rather well. The dramatic impetus of the original is lost; the opera’s structure, from overture through to damnation and coda, has gone by the wayside. But in its place we have a different entertainment that worked for its ‘new’ audience – and also for me. Duncan Rock’s Don was a memorable portrayal and both Zoë Bonner’s Leo and Helen Winter’s Marina made their marks.

Mozart wouldn’t have turned in his grave and, you know what, everyone had a good time. I was laughing happily – whereas, earlier in the day, attending a general rehearsal of La fille du Régiment at Covent Garden, I had looked on, stony-faced, at the Royal Opera’s crass attempt to embrace dumbed-down popular culture by miscasting a failed politician-cum-hopeless dancer as the non-singing Duchesse de Crackentorp. I think I’ll settle for Heaven.