Many years ago we bought a book for our son called something like "100 ways to annoy grownups". (Yes I know, what were we thinking??) Hand whistling was described in the book and after much practice blowing until I saw stars I was finally able to produce a flute like sound on demand. Pitch accuracy is very difficult and although I could at times play recognizable tunes, it did not seem like anything other than a curiosity. And then I saw these two videos on the youtube:
www.youtube.com/watch?v=u8CcHSn3Yjk
www.youtube.com/watch?v=QiIj2gDzaNI
Coalport, what do you think? If any of us can master this supremely simple yet devilishly complex instrument it would be you!