WHAT, I want to know, I say to Robin Turner, one-time Heavenly Recordings employee and now author of a book celebrating 30 years of the record label's existence, is how anyone there ever got any work done. Because, if we are to believe the account in his book Believe in Magic, back in the day the Heavenly office was party central. Mondays in the label's office were an extension of the weekend and the weekends were, frankly, messy.

"It sounds like the office was completely crazed, which it was at points," Turner concedes. "But those impromptu sessions in the office on a Monday did often spark ideas. You sat around talking cobblers with someone from the NME or Mojo and that was the way you got them to understand a band, and that ends up with them getting the cover.

"I think it's always done like that. Some will say, 'Let's go for lunch at the Ivy.' That wasn't the way we did it. We had a load of cans in the fridge. Each to their own."

Whatever the case, it has certainly worked. Some 30 years on from its first release, The World According to Sly & Lovechild, released in the summer of 1990, and, as remixed by the late Andrew Weatherall, sounding very much of its time, Heavenly Recordings is still growing strong. These days it's home to such 6Music favourites as Katy J Pearson, Baxter Dury and Working Men's Club.

The brainchild of label supremo Jeff Barrett, it has survived changing musical fashions, corporate politics and personal excesses to remain a vibrant force in the 21st century. Quite an achievement given how the music industry has been turned on its head over the last 20 years. Many of the labels that were Heavenly's near contemporaries – the likes of Factory and Creation, both of which Barrett worked for before setting up Heavenly – have long since disappeared.

The secret of the label's success? "I don't think it's ever been afraid to take risks and follow an instinct," Turner suggests, "even if the instinct is completely outside what anyone would expect."

It was ever thus. Heavenly was born at the height of acid house. Indeed, it might not even exist if it hadn't been for acid house. And yet, just to be contrary, one of label's first signings was a Welsh punk band. Yes, it was Barrett who gave us the Manic Street Preachers, releasing their first incendiary singles Motown Junk and You Love Us.

In its early days, Heavenly was home to Saint Etienne and Flowered Up but also to a country band from Camden, The Rockingbirds. In the years that followed it signed future Paloma Faith and Sophie Ellis-Bextor collaborator Ed Harcourt and anthemic rock band Doves and The Magic Numbers. That leftfield thinking continues through to the present day. Heavenly is where you will find the likes of Stealing Sheep and Gwenno who sings in both Welsh and Cornish. In short, variety is in the label's DNA.

What is a Heavenly band anyway? "I think it's people who know themselves," suggests Turner. "If you think about a band like the Manics, early on they knew exactly who they were. And someone like Gwenno, now, she knows exactly who she is. She was someone who had a successful album in the Welsh language and at the point where she is going to record a second album, when there are a lot of eyes on her, she decides to do it in Cornish. You think that's crazy but as she says, if she can't do it then, is she ever going to get the chance to do it again?"

The Heavenly backstory goes like this. Jeff Barrett had been working for Alan McGee's Creation label – his first job there was to tour-manage The Jesus and Mary Chain around Europe when the band were playing 15-minute sets much to the horror of promoters – when he discovered acid house and met Andrew Weatherall. Oh, and he was also sacked as Primal Scream's press agent. And then Barrett set up Heavenly Recordings.

It was very much of the moment, Turner suggests. Acid House had created a new economy. People were going out every night of the week. "Maybe they ended up becoming drug dealers, maybe they became promoters, maybe they became people who ran record labels. It just presented a whole new set of possibilities.

"There weren't DJs before. There were people who put on She Sells Sanctuary at your local night club at 11 o'clock at night. But there weren't people whose name you knew, who you went to go and see and follow. Acid House created a new template and Heavenly was part of that. It diversified, but that's the spirit of Acid House as well. It's not staying put in one thing for too long."

How much of the label is a reflection of Barrett? "Completely. It's very much down to him, but within the label everyone is allowed to bring in mad ideas. And quite often the mad ideas are the things that you maybe talk about in the pub and then, a couple of pints in, you think: 'this is brilliant.' And then it's getting into the office the next day and running with those ideas. That's the space he allowed to happen."

Over the years, Heavenly Recordings has been home to guitar bands, singer-songwriters, dream pop, electronica and pretty much every other music genre. And for a label based in London there is a surprisingly large Scottish connection. Heavenly has put out records by Dot Allison, Jock Scott, The Nectarine No 9 and even Edwyn Collins.

"There's always been a Scottish connection. It also has a really big Welsh contingent and recently a really big Australian contingent. Weirdly, the thing that has been lacking – apart from Flowered Up, The Rockingbirds and possibly Saint Etienne who are from just outside – is London-based bands.

But, he adds, "I don't think anybody is bothered that they missed out on the Libertines."

There were other bands who got away, though, perhaps most notably The White Stripes, who the label failed to land because those up the chain couldn't see the appeal. "You had people in EMI going, 'I can't see that that's ever going to sell silver.' It doesn't f****** matter. The record is great. It doesn't matter what it sells."

The thing that has helped the label over the last decade, Turner suggests, is the fact that it has been properly independent. "When I was there it was always an affiliate of a major label. It started off with Sony, then it became BMG, and then it was EMI." As a result, he says, "you are kind of hamstrung. If it was EMI and there was a Coldplay record coming your record had to get out of the way. And if the Coldplay record goes back they then look to move something into that hole in the schedule, which is why the second Magic Numbers album was kind of rushed. And it didn't help it at all.

"Now, being completely independent, you don't need to worry about huge artists coming in and taking up the bandwidth, as it were. It also means they can be pretty nimble."

So, when David Holmes turned up with a single recorded with Sinead O'Connor with profits being donated to the Black Lives Matter movement earlier this year Heavenly was able to put it out quickly.

For Turner, Barrett remains the label's secret weapon. He is why, 30 years on, Heavenly Recordings is still going strong.

“The person who signed Flowered Up and Saint Etienne is still the person signing Gwenno and Sinead O’Connor. It’s still the same person standing at the bar asking, ‘What do you want? A double?’”

Believe In Magic: Heavenly Recordings The First 30 Years, by Robin Turner is published by White Rabbit, priced £30