Former Bay City Rollers frontman Les McKeown has died aged 65, his family has told the BBC.
The Scottish pop singer fronted the Edinburgh band during their most successful period in the 1970s.
They had hits with tracks like I Only Wanna Be With You, Bye Bye Baby, Shang-a-Lang and Give a Little Love.
His family announced online on Thursday that he had died suddenly at his home on Tuesday.
Bay City Rollers became tartan-clad sensations in the UK and US in the 1970s. They were hugely successful, selling more than 120 million records.
"They were adorable. Five cute guys at once. That's the story of rock n roll," US journalist Danny Fields told the BBC.
"The invention of boy bands became an industry thanks to the Bay City Rollers."
First pair of tartan trousers
The group got together in the early 70s and found their name by throwing a dart at a map - it landed on Bay City near Michigan, according to the Official Charts Company.
Their first single was Keep On Dancing in 1971, and they had two number one hits in 1975 with Bye Bye Baby and Give A Little Love, plus chart-topping albums with Rollin' in 1974 and 1975's Once Upon A Star.
McKeown said the band's first pair of tartan trousers were inspired by a picture on a birthday card and were made by his father, who was a tailor.
The vocalist, who left school aged 15 and joined a band called Threshold, went on to join the Bay City Rollers aged 18 in 1973.
He left in 1978, as the band decided to go in a more new-wave direction under the new name The Rollers, but he later rejoined for several comeback tours and live recordings.
Recalling the 1975 tour 40 years later, McKeown said it was "crazy".
"We would go on and the police would make us stop because they just could not control the crowd," he said.
High-profile court case
When he was on a rare visit home to Edinburgh, McKeown - just 20 at the time - ran over and killed a 76-year-old woman.
The day after the accident McKeown rejoined the tour.
He said: "I can remember just being in complete shock. I don't know how long it took me to come out of that shock.
"In retrospect I should have dealt with the issue in a much more comprehensive way."
Despite some witnesses claiming McKeown was driving too fast, a court cleared him of the more serious charge and instead found him of guilty of reckless driving. He was fined £100 and banned from driving for a year.
McKeown claimed in numerous interviews that the guilt over the incident never left him, and was a big part of his alcoholism, as the Rollers' popularity waned dramatically in the late 1970s. He was also open in interviews about his trips to rehab.
Les McKeown and the Bay City Rollers provided part of the soundtrack to a particular chapter in Scotland's modern history.
At the height of their success in the mid 1970s, the Bay City Rollers were the biggest pop sensation Scotland had ever seen.
Their brand of bubblegum pop won fans across the world and they were unashamedly Scottish.
This was a time when few Scottish musicians became international stars other than traditional favourites like Andy Stewart or the Alexander Brothers.
The pop music Scottish children and teenagers loved was often from England or America. Outside Scotland, the Rollers were what we would now call brand ambassadors for their country.
It can seem preposterous to draw parallels between bubblegum pop, national identity or politics but perhaps there are some.
The Rollers loved their tartan at a time when many younger Scots associated it with an older generation or the sentimental, "kailyard" image of the country.
The peak of their success in the mid 70s coincided with a time when there was intense debate over Scotland's political future - a debate, at times, emboldened by a new self-confidence. Many assumed devolution in the form of a Scottish Assembly in Edinburgh was inevitable.
But like so many teen sensations, their success did not last.
The decline of the Rollers came around the same time as Scotland's humiliation in the 1978 World Cup in Argentina. A year later the plan for a Scottish Assembly failed to win sufficient support in a referendum.
Music can be the soundtrack to history. The Bay City Rollers unintentionally provided part of the playlist.
After he left the band, McKeown formed the pop group Egotrip, and released a solo album All Washed Up in 1979.
He toured more recently under the name Les McKeown's Bay City Rollers. They had been mid-way through a tour in Toronto as the coronavirus pandemic took hold, and had to return home quickly. The tour had been rebooked for November 2021.
McKeown told the Edinburgh Evening News last August that during lockdown he had "never had so much time off", and was usually always on the road for half of the year.
Celebrities shared their shock at the news and their own memories of the frontman on social media.
Judy Murray, mother of tennis champtions Andy and Jamie Murray, posted two pictures: one of her hugging Les McKeown at a concert, and one of her holding a tartan scarf. She captioned them with "Bye bye baby".
Guitarist Andy Scott from fellow seventies band The Sweet posted: "Over the years I got to know Les quite well. We both lived in Central London in the 80s and I would see him sunbathing and Roller Skating in Hyde Park close to our Mayfair office. Les my friend only 65, far too young."
Eighties pop singer Kim Wilde wrote: "I remember line dancing in the school assembly hall to Bay City Roller hits, Les was my schoolgirl crush."
And Midge Ure acknowledged the Rollers' eventful career. He said; "Dreadful news. A band thoroughly ripped off by everything bad about the music industry. The biggest band in the world for a time and nothing to show for it."