By Robert Plummer
Business reporter, BBC News
With reissued classic albums crowding out new artists on record companies' release schedules, you might be forgiven for thinking the music industry had left no stone unturned in its quest to recycle the past.
But while the major labels continue their endless restoration of rock's rich tapestry, a small band of maverick entrepreneurs are finding that there are still plenty of what they call "undiscovered vinyl artefacts from the annals of alternative pop history".
Are you ready for funky progressive rock from communist-era Hungary?
How about film soundtracks recorded in Lahore during the golden age of Pakistani cinema? Or maybe 1970s psychedelic Turkish protest songs?
All these and more can be found in the catalogue of Finders Keepers Records.
The label has been in existence since 2005, when it reissued a hopelessly rare avant-garde concept album by French composer and arranger Jean-Claude Vannier, best known for his work with Serge Gainsbourg.
Doug Shipton was working as a press officer with independent record company Cherry Red when he and fellow enthusiasts Andy Votel and Dominic Thomas "cobbled together" enough money to launch Finders Keepers.
"We're all avid record collectors, we all DJ in our spare time," he says.
Finders Keepers' biggest successes have come from rare Turkish music
"We do tend to lean more towards the dancefloor-friendly side of things, but really, we release whatever takes our fancy.
"I'd say some of these titles are quite outlandish, but with a bit of love and attention, anything's possible, really."
Low overheads mean that Finders Keepers is a viable concern with sales of 4,000 to 6,000 for each release.
The label's most successful albums to date have been two releases in its "Anatolian Invasion" series, by Turkish artists Selda Bagcan and Mustafa Ozkent, which have each sold 10,000 copies, Doug says.
Music, nostalgia and sex
Now approaching its fifth birthday, Finders Keepers is a relative novice in the world of esoteric reissues. The label widely credited with starting the phenomenon, Trunk Records, has been going since 1995.
Trunk was the first company to issue a soundtrack album from the cult British horror film The Wicker Man.
Subsequent releases have included the music from much-loved 1960s and 1970s children's TV series the Clangers, Ivor The Engine and Pogles Wood.
The Clangers album has been the label's most successful project, selling between 5,000 and 10,000 copies.
However, Trunk's catalogue also has its seedier side, boasting porn film soundtracks from the 1970s and other saucy ephemera - fully justifying the label's motto of "music, nostalgia and sex".
Label founder Jonny Trunk carved out his strange niche in the music business after tiring of his job as an advertising copywriter.
He began by licensing albums from the Bosworth music library, which had a large storehouse of tunes recorded for TV and film soundtracks that had never been commercially released.
"I started with another couple of guys. We had £600 each - that was our life savings - and we got the money back," he says.
"The investment keeps rolling. I don't spend any of the money and all the profits go back into new projects.
"My business acumen, if you like, is nothing more than trying to be frugal all the time."
Putting out long-lost records that few people have heard of is clearly no easy way to get rich.
Both Jonny Trunk and Finders Keepers' Doug Shipton are keen to stress that tracking down the rights to some of the more obscure items in their catalogues has taken years of research and legal negotiations.
For Finders Keepers, one of the hardest artists to locate was Turkish protest singer Selda Bagcan, who was persecuted by her country's military rulers in the 1980s because of her political lyrics.
Jonny Trunk sees some of his releases as "art projects"
"We spent a long time trying to find her," says Doug.
"She did actually reply to us on several occasions, telling us that she was dead, in order to throw us off the trail.
"She did relent in the end and allow us to come and visit her."
One of the oddest stories lurking behind Jonny Trunk's odd repertoire concerns the album Music For Biscuits by the Mike Sammes Singers.
Sammes and his vocal group provided backing vocals on many British pop hits in the 1960s and 1970s.
The singer died in 2001, not long after Jonny had made an initial attempt to get in touch with him.
Thanks to the intervention of a neighbour, Jonny ended up releasing a collection of unreleased Sammes tapes that had been discarded by house clearers and thrown in a skip.
"They'd unscrewed and taken away anything of any value and left these piles of beautiful manuscripts and all his old songs he'd had transcribed," says Jonny.
"After spending a day there, I found this tiny little box of all these little showreels, which I thought needed preserving.
"It's a bit like an art project, that one. But this is my sort of thing - slightly esoteric, bit curious, daft recordings which make good listening."
In fact, Jonny Trunk is quite prepared to release albums that appeal to a highly restricted audience, giving his reissue of avant-garde music pioneer Desmond Leslie's recordings as a example.
The Clangers soundtrack is Trunk's best-selling release
"He made really unusual recordings using vintage techniques. When I say that, it means throwing electric fans into pianos and that sort of thing.
"You're going to sell 500 copies of that, probably, if you're lucky, because it's weird," he says.
"But then something a bit more obvious, you might sell 3,000 or 4,000. It depends which way the wind's blowing."
However, he adds that the advent of iTunes and other digital music services has made it harder to sell complete albums to people who may just want to download the opening track instead.
So what kind of people seek out albums from labels such as Finders Keepers and Trunk? Who is the typical consumer?
"It's a very discerning record buyer, because they're very specialist releases," suggests Doug Shipton.
"I've always thought it's adventurous listeners, people into slightly more interesting music than you get everywhere else," says Jonny Trunk.
"It's always been off the beaten track, this kind of recording, although it's getting more popular now.
"Everyone thinks it's lucrative and it's not. It's a lot of work to not make a lot of money. So you've got to do it because you really want to do it."