“Rick was and, I later discovered, has always been a bit shy,” reflects Youth. “A bit more gentle. More spacey. David’s quite anchored. Weirdly enough, there’s nothing really that psychedelic about any of them. Yet together they make the most sublime psychedelic music ever made. There’s lots of ironic things going on there.” Youth is sitting in the spacious living room of his South London home. Behind him, bookshelves line an entire wall. There are volumes by Colin Wilson, Joseph Campbell and Freud. The Psychedelics Encyclopedia rests on The Classic Whisky Guide. Resting in the fireplace is a giant painting of Rupert Bear and the Wise Old Goat, staring out into the cosmos. A platinum disc for The Verve’s Urban Hymns, which Youth co-produced, hangs on the wall opposite, while a light fitting in the shape of a huge pineapple hangs from the ceiling. Youth has history of his own with Pink Floyd. A friend of the band’s bassist, Guy Pratt, he worked with Floyd backing vocalist Durga McBroom in Blue Pearl; Gilmour and Wright guested on their 1990 album, Naked. He worked again with Gilmour on The Orb’s 2010 album, Metallic Spheres.

As with Manzanera, Youth recalls getting a call “out of the blue from David. He always surprises me. He’s very frank and forthright. There’s no flutter or decoration in his communication. This call was last June. He said, ‘I’ve got this thing I’ve been working on, it’s not quite been working out. Could you come down and have a listen?’ So I jumped on the train, he picked me up and we drove to his farm in Sussex. David’s got this amazing studio at the top of a barn. He put on this track up there. I was expecting to hear solo material. Within about 40 seconds, it sounded like Floyd. It was absolutely magical. The window was open and there were birds singing. June in England is the most beautiful place in the world you could be, listening to unreleased Pink Floyd recordings with David, the hair was going up on the back of my arms. Then David explained that Phil had spent days going through all the tapes, and had put together these four pieces. What was interesting as well was that David had been working on it with Phil and without Phil. He said, ‘I’ve gone as far as I can, I just don’t know. What do you think?’ I thought maybe the arrangements weren’t quite right. Because some of it’s ’90s Floyd, it doesn’t sound that much like Floyd. I said, ‘Maybe I could experiment with some different arrangements and see if we can make it flow better.’ His parting words were, ‘Make sure it sounds like us!’”

Among the many marvellous treasures unearthed by Jackson and Iddins from Gilmour’s tape store was a recording dated from June 26, 1969, of Wright playing the Albert Hall pipe organ during rehearsals for the Floyd’s show there that evening. “There was 20 minutes of that,” says Youth. “I think at that point, Rick was toying with ideas for writing a symphony.” Taking all the material to his studio in Spain, he began rearranging and extending sections. As illustrative guides for Gilmour, he added guitar lines where he felt appropriate. At the same time, he was fighting a severe parasitic infection: “I thought, ‘Even if I die in a week, or a day, I’ve gotta finish this before I go – and don’t hold back!’”