Blogger has just malfunctioned and $%^&**!!! up in a major way and lost this post.
This post will be reinstated - but it will take some time as it contains lots of research, links and images
[Update: I've now heard that Blogger aborted somebody else's post today - so for those still to post, save as you go outside of Blogger and be careful. Mine aborted in the middle of some formatting changes]