It is a long time ago, and I am very late in posting, but on the subject of technical trade ranks I was a J/T AWF at Abingdon (47 and 53 Sqdn) in 1958 and was promoted to Corporal - note NOT Corporal Tech. My position and work schedules remained intact and I never understood the change unless the staff structure at Abingdon was short of Corporal grades. At the same time and in the same Radio Servicing Bay I recall Corporal Tech Del Rampling being promoted to Sergeant outside the Tech structure, so there are some anomalies here......!
I do en passant recall Changi quite well, being there when we ferried the first Beverley from UK to the all-new 34 Squadron. What a trip that was, at 100 knots flat out and the usual sequences of unreliability - and the accidental filling of the oil tanks with avgas at Calcutta.