Hurray! The internet turns up trumps once again. Back in May I was wondering what a "pargetter" was, and today a kind soul emailed me the answer:
I just happened across your blog on the subject whilst I was trying to satisfy my curiosity about the origin of the surname. A pargetter (usually spelled 'pargeter') is somebody who does decorative relief plastering on outside walls. It is mainly confined to East Anglia apparently.
So, there you go!