"Chink" is of course a word which can be used offensively, depending on context. I'd see it is more potentially offensive than "Jerry", less than "Kraut", and about the same as "Frog". And it's right to be cautious about this kind of thing.

But in this context, where Mr Wu is seen as playing a valuable social role, I'd have thought the implication is in fact anti-racist, and would have been seen at the time of the Blitz as saying something about everyone pulling together against the Nazis.

And it is also unusual in recognising that not everyone in the Blitz was ethnic-English. I think the committee here scored an own goal and probably in fact contributed to racism rather than combatted it.

Here is a George Formby site