Fleetwood Mac actually started as a blues band.
On 19 April 1967, John Mayall, the frontman of John Mayall & the Bluesbreakers, gave his bandmate Peter Green free studio time at Decca Studios in West Hampstead, London, to use as he wished. Four songs came out of the recording sessions. One of them was an instrumental called "Fleetwood Mac". It was named after the musicians in the rhythm section – Mick Fleetwood and John McVie.
Anyway, there is a song that fits Peter Green to a T, and it is a cover from Anthony "Duster" Barrett
"Duster", based in London, his first album Smiling Like I'm Happy saw him playing as a one-man band, playing a bass drum with his foot and blowing a harmonica on a rack while strumming a 1952 Les Paul Goldtop guitar given to him in 1968 by Peter Green.
Anyway, here is that song:
Peter Green - Jumping At Shadows
In 1974, Peter Green was diagnosed with schizophrenia.
The music of Fleetwood Mac itself is in some instances quite well done, although as the drugs took their toll things got more sporadic. (Parts of Tango In The Night recover well.) But the lyrics and stories behind them are in so many cases just a bunch of confused, well, muck, to be honest.
I went back and re-read the lyrics to “Sara” again. It’s supposed to be one of Nick’s better written songs? WTH - it’s a bunch of complete gunk. “This is your brain on drugs”, and evidently, at a considerably higher temperature than even somebody like Ozzy. Sheesh!