After only 8 hours or so, I managed to get some sort of grip on this XML stuff. Then I went to the pub and fortunately the Fat Bloke wasn't there.
There appear to be the usual caveats with Microsofts cunning plan for world domination which invovle making any sane person loose the will to live after trying to wade through what version of what actually works with what.
The good news is that it appears to be reasonably straightforward to write a CSV file without knowing the xml element names.
The bad news is that information on this really basic requirement is quite hard to come by.
The Reluctant Developer never ceases to be amazed (depressed) that he always appears to be the first person in the world to ever want to do a particular, seemingly basic, task.
Just lucky I gueess