I'm presuming that you will need the pilot on a ad hoc basis. I would contact your local flying clubs and maintenance engineers for recommendations. CFIs, H.O.D.s and even chief engineers will know a lot about local individuals and their suitability for your needs. As I said in a previous post there will be a lot of CPL/IR instructors, with range of experience, who are well known and working in or associated with flying clubs. Otherwise Flight International is the appropriate magazine for advertising nationally professional pilot jobs.