I've rather mellowed on the "of its time" argument.

I think, if you look at the lyrics of "Mr Wu" and other Formby songs, they exemplify a kind of playground racism - you can imagine if a song like that was on TV, the next day all the chinese kids getting that sung at them by the white kids. But at least the Mr Wu charactre is part of the community, a neighbour, a valued one at that, and a class equal.

So I think you'd have to be either stupid or a racist to sing that song now, but I don't think it's a racist song in the sense of promulgating racial hatred, or theories of racial superiority. It's just unthinking, unquestioning and parochial. "Of its time".

It is certainly not "of its time", in the way Adolf Hitler was "of his time". Quite apart from anything, you had a similarly cloying, vernacular, playground racism persisting in Britain right through the 1970s.