Ian,without the web I wouldn't know at all about that stereotype. I once searched for 'jokes about Germans' and to my big surprise found out about that stereotype (other stereotypes like 'follows even the most stupidest order' didn't surprise me, but this did). I told some friends since and none of them knew about us being humourless until I told them. By the way, one stereotype in Germany is that British humour is the best in the world. I hope that stereotype is not too far from being true.
Wolfgang