A BLEG

I know that at some point, the poet Philip Larkin, in a letter or review or essay, wrote something to the effect that he regretted the civil rights movement in America because it was ruining jazz. It was a joke, of course, but you can see the deeper point he was making. I’ve tried to nail it down, but can’t, and I’m now worrying I may be completely wrong. Is there anyone out there who knows the source?