While the Bay City Rollers would eventually become known far and wide, for years the legendary group's first incarnation was the capital's best-kept secret.
From their original line-up, only founding brothers Derek and Alan Longmuir would get to taste the unbridled worldwide fame and success that their tartan-infused 1970s period would bring.
Back in the Swinging Sixties, the Bay City Rollers were very much a local phenomenon, known to only those keeping a close eye on the music scene - including Edinburgh-born photographer Len Cumming.
In 1968, Len, then aged 18, got speaking to the band's notorious manager, the late Tam Paton, who offered the inexperienced snapper the chance to photograph his new prize asset.
Len took rolls and rolls of what are some of the earliest-known images of a group that would go on to alter pop culture in a manner not witnessed since the advent of Beatlemania.
This was the Bay City Rollers at the very start, an untamed gang of local youths who could never have imagined in their wildest dreams the incredible ride that was to follow.
"I was introduced to their manager Tam Paton through a DJ called Richard, who I worked with at Edinburgh Cameras," explains Len.
"Tam said he was looking for a photographer and that he didn't want conventional shots, so I started doing some Hollywood-style black and whites and incorporating the flash with stark shadows."
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The exceptionally rare and precious collection, which has only recently been rediscovered and digitised by Len, shows the group before, during and after a performance at the Cave nightclub off the Cowgate.
The pictures, which you can view here, show them at various points in the evening, both performing to and mingling with the audience and playfully mucking about off stage.
Dressed in mod apparel the lads, who had been gigging under the name the Saxons until August 1968, were a far cry from the plaid-clad heart-throbs that would dominate the UK pop charts for much of the following decade.
And, contrary to popular opinion, the Rollers at that time could really play.
"They were very good on stage, actually," says Len, who is now 72. "It was long before they started all that tartan stuff. I wasn't a fan of that.
"I enjoyed dealing with them - they were the least pretentious people I'd met
"All they wanted to do was to get on that stage and rock. It was tremendous, really."
Formerly a warehouse with vaulted ceilings, The Cave, Len says, was a claustrophobic venue, with sweat raining down on the crowd when it was full.
It was fitting that the boys responsible for the new Beatlemania should have their very own Cavern Club.
Len said: "It was a great little place with mock-cave paintings everywhere.
"The night I took the Rollers photos, it was heaving and hot - the sweat was dripping off the bloody walls. The atmosphere was great.
"People talk about the Cavern in Liverpool - this was just like that. It was just noise - beautiful. Great fun."
The Rollers at this time were fronted by Nobby Clark, with Derek Longmuir on drums, Greg Ellison and the late Alan Longmuir on guitar and Keith Norman on keyboard.
While future members, such as Les McKeown, Eric Faulkner and Stuart 'Woody' Wood are considered the band's classic line-up, Len says he much preferred the sound and style of the 1968 quintet.
He said: "Before they started that tartan stuff, they were good. That was when the lead singer was Nobby Clark.
"They were better than a lot of the groups at that time. They were wilder - I don't mean that in a nasty, smashing up guitars and hotel rooms kind of way, just the music.
"A lot of bands just copied, they were clones of other bands. The Rollers just played - they loved it.
"They took it seriously, but you could tell they were having fun. The girls certainly liked them."
In the years that followed, the Bay City Rollers continued gigging in Edinburgh and eventually playing small venues around Scotland and the rest of the UK.
In 1974, however, the band had changed their line-up, and, crucially, their look and sound, opting for a much more pop-friendly approach.
They had also recruited their "classic five" - the members that would score a string of number one hits and see them heralded as the biggest teen sensation since the Beatles with a loyal following from America to Japan and almost everywhere in between.
