Chiff and Fipple Forums

I saw one Copeland Whistle with Key (D) Mark on the tube and other one without Key Mark. Which one is the earlier one or the Key Mark just randomly added on the whistle?

Thanks!

Key marks and serial numbers are later whistles. I've got one from the early nineties and it just says Copeland. A friend of mine had an older one than mine and It had something like a cross engraved on it if I remember right. But my memory is foggy on that one.