D'oh!
How many hours had I been staring at this and pullig my hair out
Closed checking revealed some fields (that I'm not yet bothered about and so hadn't entered any data into) coming through as ""!
Put data into the page and resubmitted - bingo, data! Then I carefully cross-checked my name= and value= attributes on the other inputs and realised they were subtely misspelt! Aaaagh! :roll:
Thanks Marc