This post has been re-written several times, so please forgive me if it does not come across as coherent as I would like to. The main reason for the re-write was this post by Martin Wedge. Originally I planned to scrap the whole thing but maybe having a different perspective will help, I’ve deleted those parts that he covers and have tried to massage the rest into something resembling a continuous whole but there are still big gaps, apologies for that.
