"Business people think anyone who doesn't want to be rich is a nutcase." In 1970, Fleetwood Mac leader Peter Green walked away from his band, saying that he wanted to give all his money away, and make music that would bring people closer to God

"Now when I talked to God I knew he'd understand / He said, 'Sit by me, and I'll be your guiding hand'."

On October 23, 1969, Fleetwood Mac appeared on BBC television's flagship music show Top Of The Pops, alongside The Hollies, The Tremeloes and singer/songwriter Peter Sarstedt, to mime to their latest single, Oh Well, which had climbed to number 8 in the UK charts. When the band were introduced by the show's paedophile presenter Jimmy Savile, it was hard not to notice that vocalist / guitarist Peter Green - hirsute, and dressed in a flowing white robe and sandals - looked more like an Old Testament prophet than the pop star he was.

In truth, unbeknown to the millions watching his band at home, and indeed to the members of his band, the east London-born guitarist and singer was already having serious doubts as to whether it was truly God's will for him to pursue fame and fortune with the fast-rising group he'd formed two years previously with his former Bluesbreakers colleague Mick Fleetwood.

Four weeks later, on November 21, 1969, Fleetwood Mac kicked off their second full US tour of the year at the Fillmore East club in New York. Before the run closed at the city's world-famous Madison Square Garden arena on February 13 the following year, Green had had an epiphany: if this was to be his life now, he could dedicate it to helping others, by giving away his money to the poor.

"I am satisfied with what I've got," he told NME journalist Nick Logan upon his return to England. "And there are so many people who haven't got anything at all, I feel the least I can do is give away my excess. Not that I have millions and millions, but there are going to be some big chunks coming in compared to what the average man earns. I haven't had any of my song writing money yet and there's all that to give. Then there's my share of the advance from Reprise Records, £18,000. That's money to give.

"I've had these ideas for a longtime; now I'm going to act on them. There must be no starvation. Just because somebody is born on the other side of the world that is no reason why they should be starving for it."

"The very least I can do is give away that money I don't need," he concluded. "Anyone who thinks money is going to make them happy is so wrong... [and] anyone who's sceptical can go and get fucked!"

Green had hoped that his bandmates might share his charitable and philanthropic ideas. They did not. In fact they began to fear that their leader was losing his mind. That feeling only intensified following an incident in March 1970, where Green's wine was spiked with LSD during a visit to a commune in Munich, and had to be rescued by Mick Fleetwood. The drummer, and bassist John McVie, would later claim that this was the night that Green lost touch with reality: it was also the night that the guitarist revealed that he wanted to leave the group.

"It is time for a change," Green explained in the April 11, 1970 issue of NME. "I am always concerned with what is right with God and what God would have me do... that is the most important thing to me, that dominates every thought in my head. I don't feel I want to be a part of Fleetwood Mac anymore... It has become a business, and I don't want to be a part of a business."

"In other words, he added, "I am a religious nutcase."

When writer Nick Logan suggested that this might indeed be the perception given to those reading his words, Green laughed at the idea.

"It will be funny if they do," he responded. "But only the business people will, because they think anyone who doesn't want to be rich is a nutcase."

The following month, following a show with his band at the Roundhouse in Camden, north London on May 20, Green walked away from Fleetwood Mac for good.