Question Author
Sorry, I had a visitor.
Just to say Mamyalynne :if you are "flummoxed" (lovely word!) you hide it very well. While I have been trying to improve, I look at other people's questions and the answers you and a few other people provide. I have a real admiration for you all. I shan't name the other members of the pantheon, for fear of leaving some worthies out but you certainly are there!
And thanks for your help with this particular puzzle.
Alan