Earlier this year, rap group The Wu-Tang Clan announced that it would be creating a one-off album, featuring 31 new tracks created over a nine year period. Only one copy would be pressed and it would be auctioned the highest bidder.

Now some details of the bidder have started to emerge. An "American collector" bought the copy of Once Upon a Time in Shaolin for "millions".

For his or her money, the buyer gets the only copy of the album in existence - even the masters have been destroyed or deleted - and can listen to it at their leisure. However, no digital rips will appear online as part of the deal included a restriction on public release. The buyer cannot release any aspect of the recording for 88 years.

That clause was presumably added so a music label didn't snap up the record and release it.

Rather than to raise money, with some of the proceeds being donated to charity, the Wu-Tang Clan devised the project as a way to highlight ownership of artistic works and as a stand against music piracy.

"We pioneered a new type of intellectual property regarding the sale of a work that is simultaneously physical and digital, creating previously unexplored legal protections for a unique work that cannot be reproduced," said Alexander Gilkes, co-founder of Paddle8, the auction house that sold the album.

"From the beginning, we hoped that this concept would inspire debate and new ways of seeing creativity," added Wu-Tang Clan member RZA.

The buyer also received a pair of customised PMC MB2-XBD speakers to use while listening to Once Upon a Time in Shaolin. The album came in a silver-plated jewel case, with a 174-page leather-bound manuscript explaining the story behind each track.

It is believed to now be the most expensive record ever bought, beating Jack White's purchase of a rare Elvis Presley acetate for $300,000.