I'm nowhere near the stage of needing to employ somebody but if I did this would be the worry for me.Unless it is a family member or close friend who's totally trusted I think people would be too tempted to take the customers on their own.On the flip side,if I had been doing a customers windows for years and being paid a tenner for a job that I know is worth 15 or 20,it would become a bit galling.Especially if,like you say,I knew the customer better than my employer did.Legally,surely,you don't have a leg to stand on.Tricky one.