The song was released on Spotify last Friday, with Pink Floyd's official Twitter account promising that the rest of the catalogue would be unlocked once it passed 1m streams.
Pink Floyd is the latest major artist to join Spotify, as it tries to convince more music fans to pay up to £9.99 a month for its streaming service, rather than buy songs and albums as individual downloads from digital stores such as Apple's iTunes.
"It's a great day for fans of prog rock, but it's also a great day for younger fans who have yet to be really turned on to the magic of Pink Floyd," said Ken Parks, Spotify's chief content officer. "That's a lot of what this is about: bringing a new generation of fans to one of the biggest and most iconic bands in the world."
Spotify has more than 24 million active users, with 6 million of them paying for its service and the rest using its advertising-supported free option.
The company signed an exclusive deal for Metallica's back catalogue in December 2012, and persuaded Paul McCartney to return his archives to Spotify in November 2012, after they had been removed from all streaming services in 2010.
Spotify does not have exclusive streaming rights for Pink Floyd. The band's catalogue has been available on rival streaming services such as Rhapsody, Rdio and Deezer for years – albeit only for paying subscribers.
The sticking point with Spotify was its refusal to block its free users from streaming the albums too, as Pink Floyd's manager Paul Loasby explained at a music industry conference in February 2012. "When it came to renewing our deal with EMI, we decided we did not want to go with ad-funded, but agreed to go on subscription ones. But when we went to Spotify's office in 2010, we were declined – it was all or nothing."
In 2013, it's now all. "They decided, quite wisely I think, that this is the future of music consumption, that it helps them reach deep into a demographic that is not their core demographic, and that it's a place they need to be to secure their legacy," said Parks.
Pink Floyd's change of tune reflects a wider debate within the industry about the merits of streaming services like Spotify, and whether they can help reverse the decade-long decline in recorded music sales.
Spotify's per-stream payouts for songs played by its users are low. At the accepted industry average of just under 0.4p per stream, 1m Spotify downloads pays out around £3,800 – small beer for a band like Pink Floyd, whose career album sales are counted in the hundreds of millions.
The difference with Spotify and its rivals is that they pay out for every play, meaning the royalties mount up.
Since December 2012, Metallica's 10 most popular tracks alone have been played more than 24.4m times. The Rolling Stones have several tracks whose Spotify play-counts have passed 10m over a longer period.
Spotify says it will pay more than £318m to music rights holders in 2013, but has faced criticism from some artists over the size of its payouts.
Pink Floyd's digital music strategy has sparked controversy in the past. In 2010 the band won a high court battle against their label EMI over whether their albums could be sold as individual song downloads on Apple's iTunes Store.
Three years on, the Pink Floyd catalogue can still be cherry-picked on iTunes, and now albums including The Dark Side of the Moon, Wish You Were Here and The Wall are available on Spotify to be sliced and diced into playlists however fans like.
Spotify will now turn its attention to other streaming refuseniks, such as the Beatles, AC/DC and Led Zeppelin.
"It took the Beatles a long time to come onto iTunes. That was a very mature business by the time they joined," said Parks, referring to that band's long-awaited digital distribution deal with Apple in November 2010.
"With some of these bands, it does take a long time. But we spend a lot of time talking to bands and their management about how we can be good partners for them. They can take some convincing, but for us the effort to work with a band like Pink Floyd is certainly worth it."
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