Nelson

With the sad demise of David Shepherd there has been much in the press about Nelson and why it's called that - we all know.
But I've never seen any explanation about why it's unlucky beyond my own theory that it looks like 3 stumps without bails and that's clearly unlucky for the batting side - and, as we all know, it's a game for batsman.
I think, however there was a bit of ammunition for this theory in a letter to The Times today from a chap (must be quite old) who says that when he was doing hand writtem tenpin bowling scores he was taught to always put a hat on the digits if 111 because without it was unlucky. His 'hat' would have been a straight line - like bails .