The four in the photo are Jeremy Spencer, Danny Kirwan, John McVie and Mick Fleetwood.
In fact, when the band were formed they were originally called Peter Green’s Fleetwood Mac.
Green was widely regarded as one of the greatest guitarists of all time. When he replaced Eric Clapton in John Mayall’s Bluesbreakers in 1967 after Clapton had left, Mayall had said that they’d found someone better, to which Clapton allegedly didn’t disagree. Kirwan had joined the original four members a year after they’d formed in 1968, staying for four years.
I’ve never seen an early photograph of Fleetwood Mac without Green being in it, so perhaps that’s why that particular lot sold for an amazingly high £5500 against a pre-sale estimate of £80-120!