By summer 1967, Barrett had moved to 101 Cromwell Road, where he increased his intake of LSD and marijuana in a bid to attain the spiritual insight he knew wasn’t to be found in the BBC studios or the boutiques of the King’s Road. “He was looking for enlightenment,” says Mason, “and also for that LSD enlightenment, which was very prevalent at the time and taken very seriously. If you were going to trip, you’d do it with a guide; it wasn’t like, ‘Let’s do this and then go clubbing in Ibiza.’ It was much more serious than that, and I think he reacted badly to the drug. But I think he then kept on because of what he wanted to get from it. He kept doing it when he probably should have just said, ‘This doesn’t work for me.’ And I think that’s relevant to the story of why things continued to go badly.”

Joe Boyd noticed a change in Barrett when Pink Floyd played UFO on July 28, 1967. “His face was really close to mine, and I vividly remember thinking, ‘Shit, it’s like somebody just turned out the light’, it was just blank. His eyes were very different.”

After a short break on the Balearic island of Formentera – “If someone had written it down, and put it in front of us,” says Mason, “we still wouldn’t have recognised it; we would have thought, ‘Maybe we’ll give him two days off and it’ll all be better’” – work began on the follow-up to Piper.

“The music business destroyed Syd, really,” says Andrew King. “Everyone says he had some bad friends that played some nasty druggy trick on him with LSD and so on, but really it was the pressure. It’s the pressure of saying, ‘You’ve got to do something. Come on, Syd, give us our next hit single.’ When you have a successful little group like that – it wasn’t making gallons of money – then so many people are dependent on Syd writing another hit. Once a band gets going, there’s 30 or 40 people whose incomes depend on the band coming up with the goods. And the band were saying, ‘Come on, Syd, you’re the one who writes the hits.’ That’s what ‘Vegetable Man’ was all about.”

Released on The Early Years for the first time officially – it’s been available in poor quality on bootlegs for years – it’s astonishing to hear “Vegetable Man” as it was intended. As propulsive as “Arnold Layne”, as raw as “Lucifer Sam” and as psychedelic as “Astronomy Domine”, the song is one of Barrett and the Floyd’s finest moments, with the frontman cataloguing his paisley shirt, his yellow shoes, his box-bought pants and his black watch, before calling out, “Vegetable man/Where are you?”

“Syd wrote it in my flat,” explains Peter Jenner. “He was there prior to going to the studio. It was like, ‘Hey, we’ve got a session booked, so we’ve got to have a song’, so he wrote that. It was a description of himself. Maybe you could see it as a call for help.”

“I should think we heard the song in the studio,” remembers Mason of the sessions at London’s De Lane Lea Studios, “and played it almost immediately.”

“Syd had an indelible sense of humour,” says Andrew King of the song, “even in his darkest moments. Everyone really wanted ‘Vegetable Man’ to be a commercially feasible track – you can hear everybody under the sun singing in the chorus at the end. But nothing happened. It just disappeared into the archives.”

The fate of “Vegetable Man” remains something of a mystery, with Mason suggesting that the song was unfinished, despite its pristine sound on The Early Years. The group attempted another few tracks around the same time, which were, again, considered as singles but shelved by the group or EMI because of their disturbing nature. The more unhinged, spacey “Scream Thy Last Scream” is also included on The Early Years in astounding quality, and takes Barrett’s more childlike writing in a darker direction, with Nick Mason gabbling about an “old woman in the casket” over vari-speeded vocals, time changes, sheets of Telecaster clang and Rick Wright’s wah-wah’d Farfisa. It all devolves into a chaotic, thrilling improvisation. “She’ll be scrubbing bubbles on all fours,” mutters Barrett, sounding blank and lost in the fog of sound.

“I sing on ‘Scream Thy Last Scream’ and I think the others were jealous,” laughs Mason, tongue somewhat in cheek. “Why did I sing on it? I think it was probably Syd being a bit mischievous.”

“It’s an amazing song,” says King. “You just wonder what would have happened if Syd had stayed on top of things – or if he’d wanted to stay on top of things. Where his songwriting was going was utterly unique. ‘Scream Thy Last Scream’ is a masterpiece.”

“I can see why their record company and everybody would have recoiled from ‘Vegetable Man’ and ‘Scream Thy Last Scream’,” Peter Jenner counters. “Those songs were about the decline into confusion. Both of those are really great tracks in terms of understanding what was happening in Syd’s head. The band was breaking up, we were breaking up with the band. It was sort of ‘send for the men in white coats’ for all of us. It was all going pear-shaped, all that early optimism was going. Financial problems. Syd was clearly disturbed, the band didn’t know how to cope with him, we were trying to keep them all together. I had no experience – I mean, I’d only been in the music business for about a year. I didn’t know what I was doing. None of us did. You’ve got to understand that they were just students in an amateur band that suddenly, in the middle of a sort of social turmoil of underground-ness and hippy-ness [found success]. They weren’t particularly hippy. Syd and I, and Andrew to a lesser extent, smoked dope and took the very occasional trip. Syd had some friends who were definitely dopers, but the rest of them were much more into beer and cigs. Roger would go down the pub.”

“In The Beechwoods”, again surfacing on The Early Years for the first time, is a lighter, more melodic piece, bounding along on clipped guitars and shape-shifting organ. It certainly has single potential, and was again considered as such, but it was never finished, with Barrett’s vocals remaining unrecorded. “They were disjointed,” says Mason, “but there were songs that could have been [released], if Syd had been in a better place. They’re unfinished, inevitably, and ‘Beechwoods’ is the least finished of all of them. I think it’s missing a middle-eight.”

Another new Barrett composition, “Jugband Blues”, a warped and painful ballad featuring a lysergically dissolving brass band, was attempted later on in October 1967. “I’m most obliged to you for making it clear that I’m not here,” Barrett sings, addressing either his bandmates or the music industry. The session at De Lane Lea saw a disagreement between Barrett and Norman Smith, over the Salvation Army band who were to feature on the coda. “Norman wanted to write arrangements [for the Salvation Army band] and Syd wanted them just to make a lot of noise,” says Andrew King. “I think Syd won in the end. They do play something, then it breaks down, so I think it was a compromise in the end. But ‘Jugband Blues’ is a heck of a song, isn’t it. That lyric…”

“Norman was a musician,” says engineer Peter Mew, who worked with Smith and the Floyd on 1969’s Ummagumma, “and he had grown up in the era of three sessions a day, you make an album in three sessions, a single in a single session. The Floyd’s process was a little bit alien to him, I think.”

“I think Syd probably found him more difficult than the rest of us,” recalls Mason, “but I think by the end of it we knew we were less suited to each other. I remember a big thing was when we were recording the title track of A Saucerful Of Secrets [in 1968], and Norman was saying, ‘Well, it’s fine to let them do this, but I think after this we’re gonna have to buckle down.’ And I think then one knew that it wouldn’t work.”

On October 20, the group improvised a freeform soundtrack for one of John Latham’s experimental films, laying down a long bed of avant-garde clicks and scrapes without a semblance of melody or rhythm – absent even from bootlegs, the whole left-field suite is being released on The Early Years. Unfortunately for Syd, however, this was just a diversion before the grinding search for a commercial single continued.