That takes me back to a comic annual story (possibly Valiant) about two cat rivals (one posh the other a street cat) putting aside their hostilities to battle an invasion of rats headed by a king rat. They beat them and kill the king but are both very badly injured. The street cat which was the newcomer limps off into the sunset...
Lord Digby I think was the posh cat and was white. The street cat was black
I think Paul McCartney must have read the same story as years later he wrote a song about cats living together in a piano.