LONDON—Francis Bacon apparently wasn't a big fan of Henri Matisse.

In some previously unreleased tapes of Bacon talking off the record with his biographer, Michael Pappiatt, in 1987, recently played for the Times of London, the British master sounds off about Mattisse, saying: "I’ve never liked his things very much, except the very, very early things... I loathe them. I can never see what there is to it, with all those squalid little forms. I can’t bear the drawings either — I absolutely hate his line. I find his line sickly."

Peppiatt opted not to publish the comments at the time because he thought Bacon might object, but he recently rediscovered them while preparing for a new biography being released by Yale University Press to coincide with the Bacon retrospective opening at Tate Britain today.

"I was surprised to find quite a few things that 25 or 30 years ago didn’t seem so important," Peppiatt said. "Now we regard Bacon with such fascination that even the odd asides become significant."

Speculating on why Bacon so disliked Matisse, he used the French artist's odalisques as an example: "The odalisques were everything Bacon isn’t. They are very fluent, fluid, easy, graceful, harmonious — and Bacon is the opposite of all that."