Two, now both retired. Jake Jackson formerly of OATS now retired to France and Dave Humble ex manager flight training of BIH Aberdeen.
Jake was my first instructor and had the amazing knack of beating his incredible standards into people without their noticing the huge level of work he was putting them through.
Dave Humble appeared to have been born to fly and was the finest IF instructor I have ever seen at work. His demonstration of an ILS flown from DH to the hold in reverse left me agog (in a S61 sim).
Thanks to both of these men and many other instructors and training captains I have had a varied and thoroughly enjoyable career. I'd hate to have to get a job!