My father was at Fettes too (as a child, not a teacher). I think you may have been just before his time at Abingdon. Your son would have known him if he was in the lower school as he was in charge of it by that point. But I’m not sure how much he taught the middle or upper school. He retired around 2003 and died in 2012. The school now has an award named after him (the Dillon Cup), according to my mother. :)