Thanks for your replies Tony. Again, although he is the nominated engineer, I paid for his exams and the registration fee etc. He is currently on £27k but I think I could stretch to £30k as work is good at the moment and he is a real asset to us.
I appreciate that it's a long day traveling to London, but essentially that's where the work is at. If he wasn't willing to go there, I don't think he'd find full time employment just working locally.
There is your answer if he's as good as you make out then pay him the dollar