Four Dutch artists from the 1960s collectively called themselves The Fool.
They were close friends of The Beatles, Cream and The Hollies.

The Fool helped colorize the 1960s.
They designed clothes, painted psychedelic murals (including The Beatles’ Apple Boutique) and guitars belonging to Eric Clapton and George Harrison.
Their debut album (shown above) was produced by Graham Nash.

The Fools were Simon Posthuma, Marijke Koeger, Josje Leeger and Barry Finch.

Little is heard from them these days.
They have become a mere footnote (albeit an important one) in Beatles and Cream history.
But Simon Posthuma wrote his autobiography (in Dutch) and I recently came across this brief interview Posthuma gave after the book was published.