Adrew
If your dates are correct, he left the OCU as a "C" Cat on 17/12/64 and was reassessed only one month later as "B" (Above Average) Cat on 29/01/65. (The "B" Cat on 29/01/65 and "C" Cat 3 days later are probably such as Flying Cat and Ground Cat on the same visit by the examiners). Then only one year later on 18/02/66
he is an "A" (Exceptional) Cat -rarely given. He must have been an experienced pilot on type returning to the Shackleton Force after a Staff or CFS Tour. Such
meteric progress of somebody new to type would be unheard of on any other force;
Just reread your # 12 which confirms my thoughts. Validity of Cats was generally "D" Cat 6 months, "C" Cat one year, "B" Cat 18 months, and "A" Cat two years.