After a few years of steadily mounting success back home in Australia, future hard rock giants AC/DC embarked upon their first U.K. tour on April 23, 1976. Only problem was, this international concert debut took a few weeks longer than expected, so let's back up a bit.

As bassist Mark Evans explained in his revealing memoirs, Dirty Deeds: My Life Inside/Outside of AC/DC, "We landed at London's Heathrow Airport on April 1, 1976 [after] an extremely long flight, with stops in Singapore, Hong Kong, Mumbai, and Bahrain. I was in transit for thirty-six hours and forty-five minutes [and had] time for two hangovers on the way."

But, as it turned out, the day’s April Fools’ joke was on AC/DC because their previously planned tour with Backstreet Crawler, led by Paul Kossoff of Free, set to start a few days later, had already been canceled. Kossoff had tragically died of a heart attack on March 16 while mid-flight from Los Angeles to New York.

In any case, after clearing customs and meeting up with their managers for a quick tour of London Town, the members of AC/DC settled into a communal band house at 49 Inverness Terrace, in the suburb of Bayswater, there to wait for their tour to be rescheduled. At last, a warm-up gig at London's modest Red Cow pub was put on the calendar for April 23.

In the words of their booking agent Richard Griffiths -- interviewed for Clinton Walker's must-read tome, Highway to Hell: The Life and Times of Bon Scott -- it was "probably the greatest show I've seen in my life. [AC/DC] were doing two sets, and to start with there were probably ten people in the pub. [The band] did the whole number, Angus [Young] on Bon's shoulders, everything, I'd never seen anything like it. Then the place emptied. About half an hour later, [AC/DC] came out to do the second set and the place was packed. Everyone had run off and [told their friends] 'You have got to see this band.’"

After this auspicious introduction to London, AC/DC was literally off to the races, with a helping hand from critics, including the NME's Phil McNeill who wrote, "In the middle of the great British Punk Rock Explosion, a quintet of similarly ruthless Ozzies has just swaggered like a cat among London's surly, self-consciously paranoid pigeons ... and with a sense of what sells rather than what's cool, they could well clean up."

AC/DC's next gig was at London's Nashville Rooms, itself a home to many punk gigs (the Sex Pistols had played there just a few weeks earlier) and, after that, the band's first proper U.K. tour finally began -- amazingly still supporting a hastily reconstituted Back Street Crawler, completed by the not-quite legendary Geoff Whitehorn on guitar.

But, as documented in Walker's book, even critics who were still bullish on the de-fanged Crawler, such as Sounds scribe Phil Sutcliff, knew which way the wind was blowing, writing that "the mere wildly exciting excellence of AC/DC could not be forgotten. It shouldn't be. They are heavy, will be huge."

Of course no one could have possibly imagined how huge except, perhaps, the Young brothers, whose indomitable drive to succeed would guide AC/DC's career, through thick and thin, and past every significant career milestone, beyond this, their virgin British tour.

AC/DC Albums, Ranked Worst to Best