Talk about a pivotal moment: Intended as a triumph for Diamond Head it became just the latest disaster.
But out of it came a meeting which ensured the Wollaston group's status as a key influence in heavy metal music.
The story, in guitarist Brian Tatler's autobiography Am I Evil? (the answer is: far from it, but he does write wicked tunes) could give a traditional panto a run for its money: hard-working, good natured lad, often scorned and badly- treated by his "family" – the group he formed, and its managers – treats a passing stranger kindly, to be rewarded, some time later, with an honoured place in rock history – and he's featured in a BBC4 series Metal Britannia this month to prove it.
The stranger was Metallica drummer Lars Ulrich, and though you would be looking at him for a long time before the words fairy godmother came to mind, that's what he became to Brian and the rest of Diamond Head.
With the group booked into the wrong Odeon in London ("remote" Woolwich, not Hammersmith) for their showcase gig, and police advising everyone to stay at home because of rioting, 17-year-old Lars was one of a handful of diehards who turned up to see the band – and he'd flown from Los Angeles.
That his favourite band was Diamond Head came as such a pleasant surprise to Brian that he invited him to stay at his home for a week, and travel around with the band, after which Lars spent a month at singer Sean Harris's home.
Four months later Lars was drumming with Metallica, who soon recorded a cover version of Diamond Head's Am I Evil? (and in their early shows covered about six Diamond Head songs) and at every opportunity Lars would pay tribute to the Wollaston band as Metallica's big influence.
But the main theme of this well-written, honest, and highly entertaining book is a sad one: how one of the best of what were called the New Wave Of British Heavy Metal bands failed to win the fame they deserved.
It was something that even strangers could spot: The only thing Twisted Sister's Dee Snyder ever said to Sean was: "You need a manager."
As it was they stayed with the ones they had from the start: Sean's mum, Linda, and her partner, and booking the wrong Odeon was far from their worst mistake.
"Says Brian: "There came a point where they should just have walked away or retained a small interest in the band.
"Our record company, MCA, called a special meeting and said either we change our management or they wash their hands of us, and that's exactly what happened, he walked out of the boardroom and we never saw him again."
There were plenty more arguments and heartbreak for Brian, who formed the group when still at school, talking his best friend Duncan Scott into playing the drums, teaching Colin Kimberley to play bass, and recruiting Sean as vocalist.
"Sean was a friend in my year, but we weren't close until I heard he could sing. He sounded great straight away and got better and better."
It's a well-known story to rock fans, but Brian's book brings it brilliantly to life, either playing with Diamond Head, or, in the two large gaps in their career, a group called Radio Moscow, running a studio in Lye called RPK as producer engineer, then, in the second gap, Quill and a Thin Lizzy tribute band.
What helped was the friendship with Metallica, who by 1990 had recorded three Diamond Head songs. Royalties for the two writers began to creep in in the mid-80s, but it wasn't until a lot of squabbles later that Brian began getting his rightful due.
It also brought about Brian's most memorable show: at Milton Keynes Bowl in 1993, opening for Metallica, and Megadeth (a rare occasion when the opening group were avidly watched by the bill toppers – Megadeth's Dave Mustaine listening with his head out of the tour bus's sunroof).
Brian and Lars are still buddies and soul mates, but he and Sean have not met since 2004.
Now Diamond Head are looking forward to their tour of Britain this month, supporting Europe. They're at the O2 Academy in Birmingham on February 19, and feature Brian, Nick Tart (vocals) Karl Wilcox (drums), Eddie Moohan (bass) and Abbz (guitar).
By John Ogden