In the early days of Pink Floyd, Syd Barrett was the group’s undisputed leader. His psychedelic and often whimsical style of songwriting perfectly encapsulated the heady spirit of the late 1960s and the hippy dream.

Barrett’s compositional method has been called naïve, but it is perhaps better described as childlike, often effortlessly inhabiting the worlds of dream, mystery and the subconscious.

He was a wonderfully instinctive guitarist, and his highly original use of slide and echo was able to translate the hypnotic atmosphere that Pink Floyd generated on stage to the albums they created in the studio. These are memorable as few others of their era are.

But Barrett then fell victim to the darker side of those heady times, as his copious indulgence in hallucinogenic drugs pushed an already fragile psyche over the edge.

After dominating Pink Floyd’s early material and writing their first two hit singles, by 1968 he found himself forced out of the group on account of his erratic behaviour. Without him, they went on to become one of the biggest-selling acts of the 1970s and 1980s, while his output was restricted to two strange but compelling solo albums, which reflected his precarious mental state and are today regarded as cult classics.

After that, the rest was silence, as he became a recluse and abandoned all involvement in music. Yet although he did not release another record after 1970, he continued to exert an eerie fascination for generations of future musicians — perhaps because his fate reminded them of the slender thread by which creative talent can hang.

The son of a Cambridge pathologist, Roger Keith Barrett fell in love with rock’n’roll in the late 1950s while at Cambridge High School. He earned the nickname "Syd" at a local jazz club after a drummer of the same name and by the early 1960s was in his first group, Geoff Mott and the Mottoes.

The line-up also included future Pink Floyd colleague Roger Waters. After a brief spell in another local R&B band, Those Without, Barrett moved to London in 1964 to attend Camberwell Art College.

There he was reunited with Waters in a new band, which already included the drummer Nick Mason and Rick Wright on keyboards. After trying various names, including the Spectrum Five and The Tea Set, they settled upon the Pink Floyd Blues Band.

Barrett had coined the name as a fusion of two grizzled bluesmen called Pink Anderson and Floyd Council, although hippy romantics will always prefer the story he later told of the name being transmitted to him by a flying saucer while he was sitting on Glastonbury Tor.

At first, the group played mostly R&B covers. But Barrett had begun experimenting with LSD in 1965 and the experience began to inspire his own songwriting. As the nascent post-beat, drug-based hippy sub-culture gathered pace throughout 1966, Pink Floyd — as they were now called — effectively became its house band. The R&B covers gave way to Barrett’s quirky songs and long, improvisational "space" epics, with titles such as Interstellar Overdrive and Astronomy Domine.

By early 1967 all of the main record labels were looking to sign one of the new psychedelic groups. Pink Floyd, who had built a sizeable following at all-night underground London clubs with names such as Middle Earth and UFO, were top of most A&R men’s lists and, after turning down a deal with Polydor, they were snapped up by EMI.

Not that the company was totally aware of who or what it had signed. When the group were introduced to the label’s executives, one of them reportedly demanded to know which one was Pink. EMI was also concerned by the band’s druggy image and felt obliged to issue a press statement insisting that the term "psychedelic" referred to the effect created by the light show which accompanied the Floyd’s live performances, and had no connection with drugs.

The band had already recorded Arnold Layne with the producer Joe Boyd before signing, and the song became Pink Floyd’s first single. Despite Barrett’s lyrics about transvestism, it somehow escaped a BBC ban and reached number 20 in the charts. The follow-up, See Emily Play, did even better. It reached number 6, found the band miming on Top Of The Pops and was later covered by David Bowie. The two songs were undoubted masterpieces of early psychedelic pop and are the bedrock of claims that Barrett was a "genius".

Pink Floyd’s debut album, The Piper at the Gates Of Dawn, followed in August 1967. With its title borrowed from a chapter heading in The Wind in the Willows, the record marked the high tide of the "summer of love". But by now, Barrett’s behaviour was growing increasingly erratic. He was ingesting LSD on an almost daily basis and began missing gigs. When he did turn up, he often resembled a zombie on stage who would play one note all night.

As the main songwriter, there was also pressure on him to come up with another hit. The third Pink Floyd single, Apples and Oranges, contained flashes of his earlier inspiration but failed to chart. Stories began to circulate that all was not well in he Floyd camp, and by the autumn of 1967 the rest of the band were determined that he had to go.

There was a half-hearted attempt at a compromise when the guitarist David Gilmour, an old Cambridge friend with whom Barrett had spent the summer of 1965 busking in the South of France, was recruited to bolster their live performances, with the intention that Barrett should concentrate on writing songs. But he seemed incapable even of that, and halfway through the recording of their second album, he was ousted for good.

When Saucerful Of Secrets was released some months later in June 1968, Barrett’s contribution had not been erased. But his spectral presence only served to make it clear that he had ceased to be the driving force long before he was kicked out. The album concluded with his Jugband Blues, a song with a harrowing lyric in which he appeared to be describing his own schizophrenia.

After receiving psychiatric treatment in a Cambridge hospital, he was coaxed back into the studio and spent 15 months intermittently recording his first solo album, The Madcap Laughs. In contrast to Pink Floyd’s elaborate arrangements, the songs sounded threadbare and even slapdash, and recording them was a maddening process.

Peter Mew, the EMI engineer who worked on the sessions, described Barrett as "not on the same planet as the rest of us". Gilmour and Waters, perhaps feeling guilty for pushing him out of Pink Floyd, eventually offered Barrett assistance to salvage something from the tortured sessions. Eventually released at the beginning of 1970, somehow it worked and The Madcap Laughs includes some hypnotic and ethereal moments, such as Golden Hair, a James Joyce poem set to music by Barrett.

Almost immediately, Barrett began work on a second album, with Gilmour as producer. On its release that summer, he even attempted a return to the stage. But four songs into the set, he decided he wasn’t enjoying himself and put down his guitar and walked off. It later emerged that he had returned to Cambridge and was living in the basement of his mother’s house.

There was one more attempt in 1972 at putting a new band together, called Stars, but they fell apart when he stopped turning up for gigs. A last effort at recording some new songs in 1974 was aborted when it became obvious to all concerned that his muse had finally deserted him. It was the end of his musical career.

Yet he was far from forgotten. In 1975 Pink Floyd paid tribute to him in a song called Shine on You Crazy Diamond on their multi-platinum Wish You Were Here album. The lyric poignantly remembered how in earlier days his eyes had "shone like the sun" but now looked "like black holes in the sky". He had turned up during the recording sessions for the album at Abbey Road and his old band mates had not even recognised him.

He spent the rest of his years living quietly in Cambridge, although for a time he also kept an apartment in Chelsea. His royalties from early Pink Floyd recordings ensured that he did not need to work and he passed much of his time painting. Fans who hunted him down found a remote, balding and heavy-set man who was unwilling — or unable — to talk. In 1987 The News Of The World knocked on his door and ran a two page "exposé" on what LSD had done to him and claimed that his drug use had left him virtually unable to string a sentence together.

That his reticence might have been because he did not want to talk to the tabloid press apparently did not occur to them. Yet although the story was cheaply sensational and caused some offence to his family, there was no doubt that drugs had contributed to his decline. The following year, his former Pink Floyd colleague Rick Wright claimed: "If he hadn’t had this complete nervous breakdown, he could easily have been one of the greatest songwriters today."

Such comments only helped the legend to grow. In 1988 previously unreleased solo material was issued on the album Opel. Five years later his collected solo works were repackaged in a lavish three-CD box set. In 2001 came another compilation, Wouldn’t You Miss Me? — The Best of Syd Barrett. A biography, Crazy Diamond, written by Mike Watkinson and Pete Anderson, was first published in 1991, and an updated edition — including reports of new "sightings" by fans — appeared ten years later.

Yet Barrett remained uninterested until the end. An offer from Atlantic Records in the mid-1990s of £200,000 for "three or four songs" to be recorded at his convenience in his living room was ignored. And although he was said to have found some contentment in later years, his death brings to an end one of the most enigmatic and saddest stories in rock’n’roll.

Syd Barrett, Pink Floyd founder and songwriter, was born on January 6, 1946. He died on July 7, 2006, aged 60.