Jenner hummed Love out of tune
Interstellar Overdrive, the long instrumental on The Piper at the Gates of Dawn, started when Peter Jenner hummed Love’s My Little Red Book to Syd Barrett out of tune. Love’s record was a cover of the Burt Bacharach and Hal David song. Jenner, the band’s co-manager, tried to show Barrett the riff by singing it. He could not sing it in time or in tune. Barrett played back what he had heard. It was a different figure, descending and blunt. That figure is the song. There are no words.
The album version was recorded at Abbey Road in March and April 1967. Norman Smith produced it. EMI Columbia released The Piper at the Gates of Dawn in Britain on 5 August 1967. Barrett plays the riff on guitar. Roger Waters, Rick Wright and Nick Mason play with him. The shape is simple. The riff opens, the band leaves it for a free middle, and the riff comes back to close. Smith had them play the piece twice and laid one performance on top of the other, so the album track is a double-track of the whole take, not a single pass.
An earlier, longer version had already been taped in January 1967 at Sound Techniques, for Peter Whitehead’s film Tonite Let’s All Make Love in London. That recording is the soundtrack version. The record that counts here is the Abbey Road one, about nine and a half minutes, on Piper. The free middle is the part that matched the 1966 and 1967 live shows, when the riff was only the door in and the door out. Smith, an EMI staff producer, kept that stretch on the album instead of cutting the song down to the riff.
I hummed Love’s version of My Little Red Book to Syd. I was so out of tune that what he played back was a different song.
(Peter Jenner, on the riff of Interstellar Overdrive)

Barrett is the guitarist on this take. The riff is his answer to a bad hum, not a chart he was handed. Wright’s organ and Waters’ bass move with the free section and then lock back to the figure. Mason’s drums are doubled with the rest of the band, because Smith stacked the whole performance. You can hear the two passes sit on each other, especially when the free playing does not match exactly.
Later live versions, with David Gilmour, stretch the middle much further. They are not this recording. The Piper track is the spring 1967 Abbey Road take: the Love riff heard wrong, played twice, and left at full length. The title sounds like a space song. The music is a guitar figure and a jam in the middle. On the sleeve the instrumental is credited to Barrett, Waters, Wright and Mason, a group credit for a piece nobody wrote down. The Love single Jenner had in his head was a 1966 cover, about two and a half minutes of pop. What Barrett played runs nearly four times as long.