Only around 30 punters witnessed the fabled event, but thousands have since claimed: 'I was there'.
One man who was certainly in attendance that night is Grohl himself. And he who formed Foo Fighters from the ashes of Nirvana following Cobain's death, aged 27, says their low-key set in the South Clerk Street pub trumped even their stint on Top of the Pops.
“We just sat on these barstools and played some music,” Grohl recalls in the BBC documentary When Nirvana Came to Britain.
“I felt completely comfortable doing that. Maybe more so than anything else we were doing, like playing Top of the Pops.
“That just seemed more natural to me.
“Then I sat at the bar and someone gave me a lesson in whisky that went on for a long time.”
After pausing for thought, he adds: “The UK definitely responded to Nirvana much more, before America.
“You guys were the first with everything – we cut our teeth there.”
Just three months prior, Nirvana had released second album Nevermind, a record that would launch them into the rock’n’ roll stratosphere, with tracks like Smells Like Teen Spirit, Come As You Are, Lithium and In Bloom becoming anthems for a generation.
The Southern Bar gig came about after Nirvana agreed to appear at a benefit gig for sick kids’ hospital after being asked by Edinburgh grunge band The Joyriders.
Flyers promising ‘very, very special (American) guests’ were handed out after Nirvana’s gig at Calton Studios on November 29.
Soon rumours were swirling around town that it was none other than the mighty Nirvana who were the ‘very, very special (American) guests’ in question.
As was to be expected, a huge crowd had assembled at the Southern Bar by mid-afternoon on the day of the gig.
Not even The Joyriders were sure Nirvana would turn up, however, and by the time the Capital outfit’s set had come to an end, the boys from Seattle still hadn’t appeared.
When The Joyriders announced over the mic that Nirvana weren’t coming, most of the crowd headed for the exit.
Only a few die-hards hung around, among them long-time fan Alan Edwards, who even has the photographs to prove it.
“The guy from the band that played went up to the microphone and said ‘I’ve been told they’re not coming’,” he recalls. “Most of the bar left.”“I had this s****y camera and I’m so glad I took it,” he adds, laughing.
When Cobain and Grohl finally sauntered through the front door, about an hour later, Edwards was overjoyed.
That they turned up at all was remarkable considering Cobain was in real pain at the time, suffering from the same stomach problem that plagued him for much of his adult life.
Nevertheless, with Cobain on vocals and drummer Grohl on bass in place of the absent Krist Novoselic, two-thirds of the legendary grunge band performed a short acoustic set in front of a smattering of lucky fans.
“It was just epic,” Edwards recalls. “When Kurt screamed out the lyrics to his songs, I’ve never heard anyone with a scream like that. He could’ve stripped paint off the walls.”
Also among the contributors to the When Nirvana Came to Britain documentary are The Joyriders Murdo MacLeod and Dunsy Dunsmor.
Recalling the legendary gig in question, MacLeod says: “It was primarily a biker bar, so there was always a line of bikes parked outside on the street.
“It would always be rammed and really noisy.
“I knew Nirvana from my previous band that supported them on their first UK tour.
“We were doing a charity gig for the sick kids’ hospital.
“My brother was their tour manager and we knew they had a night off – so we asked if they’d do it and they said yes.
“People were really gobsmacked when David and Kurt showed up at the door.
“To see them with pints, strumming acoustic guitars, just being relaxed and having a blether with people, it was really special.”
Dunsmor remembers it in much the same way.
“It started getting really busy in the middle of the afternoon because word had got around,” he says.
“I remember it filling up and thinking ‘this is spiralling out of control’.
“As we went on and played longer people started leaving, there were shouts of ‘Where’s Nirvana?‘
“The vast majority of people who had been there during the day left – so there were maybe only 30 people left when Nirvana actually turned up.”
MacLeod pitches back in, laughing: “But if you were to do a straw poll in Edinburgh you’ll probably get 500 or 600 people who will tell you they were at it who weren’t.”Cobain and Grohl played five songs, and after the gig the pair stuck and happily chatted to punters.Edwards was one of them.
“I got talking to them for a little while,” he says. “They could’ve just went ‘see you later, bye-bye’ and not given me the time of day.
“They were just super-cool.”Not everyone was so laid-back though.
“One of the bouncers was getting angry because I was taking pictures,” Edwards recalls.
“Dave Grohl saw what was going on, walked over, kissed the bouncer and gave him a big hug.
“The irony is I didn’t get the camera confiscated because of Dave Grohl.”