I have exhausted Google and still can't find it. It was a children's book that I read probably in the late 1980s/early 1990s about a cat that died, and his owner (a little boy I think) was sad. I think he actually says "he's gone now, and I'm sad about that" or something like that. Anyway, the boy comes across the whole neighbourhood's cats in mourning and comes to find out that actually, the cat led a whole secret double life in the night-time and was some sort of famous singer cat. It is driving me insane, WHAT WAS IT CALLED?!