As The Jesus And Mary Chain bring their Psychocandy full-album show to the UK, Simon Price sees their Troxy show, salutes the power of myth and ponders: is it about pop versus noise, or noise versus pop?

No.1 Prince Of Wales Road in Kentish Town, an imposing Art Deco redbrick cornerhouse built in 1927, has recently been broken up into apartments and maisonettes for the wealthy. Before that, it stood empty and boarded-up for years, and before that it served as a Pizza Express. What its affluent inhabitants almost certainly don't realise is that their dream home was once the scene of a legendary rock & roll moment. Or, perhaps, wasn't.

Whether or not The Jesus And Mary Chain's infamous 'riot' at North London Polytechnic, whose Students' Union was originally housed in the building, actually justified the R-word is disputed by many who actually attended the gig. Some say it was just a bit of handbags between security and students who were miffed at being locked out of an oversold venue, and a few bottles thrown by impatient punters waiting for the Mary Chain to actually walk on.

The music press, however, reported it as a full-scale riot. And they were quite correct to, as per The Man Who Shot Liberty Valance, "print the legend". Without its myths, rock & roll is thin gruel. That's why the imagineering words-and-pictures volume Rock Dreams by Nik Cohn and Guy Peellaert is the superior of even the greatest traditional factual rock biog. The Jesus And Mary Chain SEEMED like the sort of band who inspired riots, and that was far and away the most important thing.

The Mary Chain understood the power of myth more intuitively than anyone else in the 80s bar The Smiths and Prince (those three artists, perhaps not coincidentally, were my three favourites in the world during that era), right down to the importance of telling lies about, for instance, the Reid brothers' ages being just 19 and 21. And the North London Polytechnic Riot fed into their reputation as, as one tabloid had it, "the new Sex Pistols". I bought it, completely, and utterly: everything about them from the blasphemous name to the bad skin and unkempt hair to the Ray-Bans and drainpipes to the biker jackets and Cuban heels to the insolent attitude and fuck-everything nihilism made The Jesus And Mary Chain feel like the most dangerous and sexy rock & roll band on the planet.

By the time I actually encountered The Jesus And Mary Chain's music, the exquisite hype-storm had wound me up to such a fever-pitch of anticipation that when I heard John Peel play one of their feedback-drenched tracks through my tinny clock-radio late one night in my pitch-black bedroom, I actually thought that Satan was coming through my speakers.

I swallowed and regurgitated the accompanying theory and rhetoric: The Jesus And Mary Chain were subverting 60s girl-group and surf-pop by defiling its beauty, assaulting it, vandalising it with abrasive sandpaper sheets of violent noise. But both halves of the equation were equally important: just as the distortion and dissonance provided the visceral thrills, there was also, in context of the uptight 80s indie scene, something daringly decadent – revolutionary, almost - about a band loosening the strictures and using "uh-huh-huh" and "doo-doo-doo" in a chorus, instead of feeling compelled to impart something meaningful at every turn.

Were JAMC the first punk-ish band to openly show their love of melodic 60s pop? No (New York Dolls and Ramones beat them to that). Were they the first to use feedback as a central element, not a peripheral accident? No (see Lou Reed's Metal Machine Music, for starters). Were they the first to combine those two elements? No, not even that (the intro to The Beatles' 'I Feel Fine' famously, if only for a split-second, got there first). But The Jesus And Mary Chain's radicalism was in pushing that formula to such an insane extreme that their records sounded about to collapse into entropy at any moment. Psychocandy, the classic 1985 debut which they're playing in its entirety, is such an extreme record, in fact, that in retrospect it seems incredible that a major record label – Warners, via their subsidiary Blanco Y Negro – were willing to put it out. That they did so stands as a glorious testament to the spirit of the 1980s.

Thirty years later, here we all are at another of London's salvaged Art Deco buildings, the Troxy: an entire generation of musos, journalists, indie nerds, and at least one Labour MP. Psychocandy is no longer a subversive eminence noir lurking in the shadows but a venerated and ever-influential part of the canon, and the Mary Chain are a face on alternative rock's Mount Rushmore. The still sharp-cheekboned Jim has something of a junior Pete Postlethwaite about him these days, and William's greyed-out explosion of curls now makes him look, from a distance, a bit like Miriam Margolyes. Their task is to make us forget the intervening years, and feel as transformed as we did when we first heard that record. With that much goodwill in the room, the job is half-done. With an album that great ready to be played, it's three-quarters.

We'll have to wait for it, though. Being contrary bastards whose debut single was literally about inversion, The Jesus And Mary Chain do things back-to-front. There will be no encore, Jim informs us, because to play one "seems presumptuous", and instead they're going to play a bunch of other songs first, and when Psychocandy finishes, "that really is the end".

An anti-encore, then. A run of hits: 'April Skies', second album Darklands' lead single which cracked the Top 10 by toning down the radio-hostile white noise, then 'Head On' from the sleek and underrated Automatic, then 'Some Candy Talking', which made the Top 20 despite receiving no daytime airplay (it's hard to know which was more hilarious: Radio 1's Mike Smith trying to get it banned for being a hymn to drugs, or William Reid trying to tell the world it wasn't). From the same EP, we get the fragile ballad 'Psychocandy' (the song), and then 1991's 'Reverence', their badass breakbeat-based concession to Baggy. Then we rewind to 1983 for obscure demo track 'Up Too High', after which William turns his fretboard and pick-ups to face his retro Orange amplifier cabinet, and the unholy howlround heralds their first-ever single, the brutal but beautiful 'Upside Down'. His brother, meanwhile, does that drop that he does, sliding down the mic stand into a crouch at climactic moments in the song. (Some frontmen jump around when they're getting into it. Jim Reid is the anti-frontman: when he's into it, he gets LOW.) The messing around, this tells us, is over. Here comes the hard stuff.

Well, not quite yet. It always felt like a key part of The Jesus And Mary Chain's appeal that they didn't hail from glamorous Glasgow or cultural Edinburgh, but from the unfashionable post-war New Town of East Kilbride. While they're offstage for a quick interval to quaff a pint of heroin or something, we're shown a kitschy 1954 promotional film called East Kilbride – Town Of Tomorrow, selling the suburban settlement with all the municipal optimism it can muster.

It's probably a coincidence that this dream town, with its identical Soviet-style grey housing blocks and interlinked shopping malls, is where George Orwell, in a hospital bed, wrote much of Nineteen Eighty-Four. After all, in his time, the town's own dystopian future had yet to reveal itself. Arguably, it never did: in relative terms, East Kilbride was a success story, and the overspill families from the Glasgow slum clearances who made it their home probably had a better time than if they'd stayed put.

The one major omission from the planners' blueprint, however, was anything to do for the young. And the young, inevitably, made their own amusement: drugs, minor delinquency and locking yourself in your room listening to music. You don't need to be a genius to figure out how those three factors fed into Psychocandy.

The quaint old advert is disrupted by the "dum, dum-dum, tsch" of Hal Blaine's 'Be My Baby' drumbeat, and we're into 'Just Like Honey', reclaimed at last from the overrated nonsense of Lost In Translation and restored to its proper place as the opening track on a deathless album.

They're doing it in order, then. Which means that 'The Living End' is next. William Reid once promised "we'll make a Shangri-La's record one day", and in at least one sense, 'The Living End' is it: a daft motorcycle death record, with Jim cast as the youthful narcissist, too in love with himself to watch where he's going, like James Dean hurtling at speed towards the oncoming Donald Turnupseed (or, in Jim's case, a tree), until "my head is dripping into my leather boots".

It's a toss-up as to which of the album tracks, unreleased as singles, represents the Mary Chain's most successful stab at writing the perfect pop song: 'The Hardest Walk', with the heartbreakingly gorgeous logic of its chord progression, or the concise but punishing 'Taste Of Cindy'. For me, the latter edges it: gets in, does what it does, and gets out again in 1:42, leaving you gobsmacked and making all other bands sound like flatulent hippies. Bobby Gillespie, drummer on the original, would attempt to outdo it the following year with Primal Scream's 'Velocity Girl', similar in structure but 14 seconds shorter. And very nearly succeed. But not quite.

Speaking of perfection, Psychocandy exists in the memory as a 'perfect' record, but hearing it in the flesh offers reminders that it never was. 'Cut Dead' is an interlude of dull strumming, an unwelcome harbinger of the boringness which would characterise their next record, Darklands. Tonight, even William zones out midway through it and plays the wrong chord, earning a quick withering glare from Jim. Lyrically, too, there are some clunky moments, most notably during 'In A Hole', which gives us the notorious "How can something crawl within/My rubber holy baked bean tin?" (The ever-flickering strobe makes it difficult to discern whether Jim delivers it with a straight face.) Then there's the Mary Chain's rampant recycling habit: 'Sowing Seeds' is basically '(Just Like) 'Just Like Honey'', and the riff from 'Something's Wrong' got reused on 'Happy When It Rains'. That said, sometimes these things work out better second time around. After all, what is 'Never Understand' if not 'Upside Down' only better and with a bigger recording budget?

Because this wasn't some shambolic, C86-style record, with simplistic indiepop melodies haplessly lashed with squalls of sound at random. If you played Psychocandy to death – and Jesus Christ, I did that – and learned the feedback 'melodies' as if they were iconic guitar solos, you gradually came to credit Flood, Alan Moulder, John Loder and the Reids with actual intent, and to realise that every tiniest modulation felt ORCHESTRATED.

Take, for example, the specific way that, in 'You Trip Me Up', the ear-splitting screech enters like a horizontal beam of steel just after the line "Sometimes I walk sideways to avoid you, when I've annoyed you...", and the way the howl fades away at the song's conclusion like a train disappearing down a tunnel. That song is the album's, and arguably the band's, greatest achievement, and provides the gig's most transcendent moment.

You suddenly remember, in a moment of clarity, that the pat pop-crit rhetoric of the 80s got it all wrong. Psychocandy isn't about pretty pop defiled by ugly noise. The noise IS the beauty. And it wasn't Satan I was hearing through that clock-radio speaker. It was something close to God.