According to Dennis Waterman's autobiography "ReMinder", Susan George's character Samantha Mansfield in Series 4 was written out after a few episodes because Waterman and executive producer David Reynolds decided that George was not capable of doing the job. After hasty re-writes, Leslie Ash's character Jo Blake was introduced as a replacement love interest for Thomas Gynn.
The show was originally going to be called 'Northern Lights'.
Created by Geoff McQueen, who also devised The Bill.