Solved! (well, only got xp out of one combat, but I am hopeful
)
Thought I had a clean install, but apparently Steam does not delete the \session\ folder when you tell it to delete local content and I still had:
mod_wn131_interface_v3.kfs
mod_wn131_camera.kfs
there. Removed them and xp is back! Shame as they were both brilliant, but the game was unplayable before so cest la vie.