Supremos of rock stage craft, Ratt dealt with the situation the way only they could have done, in the end giving the crowd something completely unexpected. They played a show that was jarring and fluent at the same time, breezy and engaged, at times stepping outside of their natural sonic signature and sounding completely unlike anything we ever heard from them before, for brief moments becoming an almost industrial-sounding band, jaws dropping all round the venue half in awe, half in shock.

Deciding to build the show up with balance and care, they kicked it off with low-key numbers, the Rufus Thomas cover "Walkin' The Dog" and one of their earliest songs "Sweet Cheater" among them, in no hurry to prove any credentials or to get an OTT reaction right off the bat. Rather this was a gradual getting-to-know you start to the show, as if the band wanted to see who came out to see them that evening. When it transpired that the audience was all die-hard fans and young admirers recruited by the albums, the show turned into a superb display of great musicianship (courtesy of Warren DeMartini and Bobby Blotzer) and vintage American swagger (courtesy of Stephen Pearcy).

Pearcy, wearing a leather Stetson emphasised his composure with a laidback ease, moving around the stage with calm and relaxed aplomb. DeMartini's reserved cool was contrasted by Robbie Crane’s full-on headbanging stance, while Blotzer behind the drums looked and sounded like Zeus in charge of a whopping thunder cannon.

“The Morning After” was the first highlight of the show and the 5th song of the set, when DeMartini and good old reliable hired gun John Corabi finally showed a glimpse of the rip-roaring guitar panache this band is capable of, Corabi echoing DeMartini’s blazingly hot terse phrases. After that one infectious classic number followed another, the crowd singing along and raising their hands in the air. During "Back for More", an atmospheric, hypnotic old hit with a chorus that can sway anyone into a sweet dream-like trance, the crowd let go completely, with everyone singing at the top of their lungs and cheering the fretboard pyrotechnics DeMartini set off with magnificently casual precision during his solo. He then finally fulfilled the promise of delivering a real guitar burner on "Wanted Man", when he illuminated this space-rocking oldie with an audacious paring of sharp rock chops and melodic lines full of colour and nuance, instantly connecting with the audience and making it applaud like it was an American crowd.

The powerhouse of a tune, "I'm Insane", was the showcase of Blotzer's technique when he made his drums talk, boosting the intensity of the song with explosive, precisely directed rhythmic interplay between the drums and the bass, he and Crane making the song dance its way through strutting harmonic variations. DeMartini's solo on this number was another highlight, showcasing his range, sense of melody and the sheer joy he puts into crafting his leads while retaining a perfect sense of form and articulation.

On "Lack of Communication" Stephen Pearcy sounded downright futuristic, adding reverb to his voice and making the band sound almost like a mid-‘90s industrial outfit. This felt eerily enigmatic, if not downright spooky, and if this was a preview of things to come on the band’s next album (to be released later this year), we are surely going to be in for an exciting ride.

Experimentation aside, one song that summed up the spirit of this band better than any other was "Dangerous but Worth the Risk". Contrasting a strident hook with the tantalising suspense of its brief languorous moments, it made the crowd jump each time it reverted to the unstoppable beat of the chorus, the one that never lets go once it grabs you. And once this number was over, Pearcy made the crowd laugh in an unexpected display of warmth and good humour, remarking that after an 18-year absence some of us in the crowd could be his children.

The show finished with "Round and Round", the song as perfect as pop rock gets, with its pristine harmony and elegantly alluring hook fulfilling everyone's wishes for a perfect night. The crowd didn't want to leave, and when it became clear that it was indeed all over, people finally started filing out into the chilly English night talking glowingly about what they had just witnessed inside. Some sounded excited, some tired but satisfied, some restless and refusing to go home, but everyone was talking about wanting to see this band play again in London.

Even though the Brits would never admit it, the crowd tonight, apart from hearing the band play, wanted to see first-hand what this legendary American rock outfit was going to look like. Other bands of their generation keep appearing in the UK more or less regularly, but Ratt have remained an enigma for almost two decades. Still, for many of us they have always summed up all that glam metal stood for in its heyday - the high life, beautiful clothes, gorgeous cars and stunning female companions. All this, obviously, on top of the virtuoso execution of tunes that you have to hear once to remember forever. The times have, naturally, changed, and so, we now know, has the band. There is a lot of dignity and quiet self-assurance about them now, but some things still remain true about Ratt: they boast better looks than Bon Jovi (verified through a telephoto lens yet again), have more consistency in their songwriting than Motley Crue (confirmed on the night), and DeMartini's guitar attack blows away most of the highly praised axe-slingers of his generation (proven true again live). Their new album is the next thing the UK is now waiting for, as well as more shows on our side of the Atlantic. Because another 18-year wait after such an uplifting tour would be just silly, wouldn’t it?