The wearing of shorts with a jacket and tie is a legacy of the dress pre-war. I don't know when it changed but as TTN says; mid-60s the jacket and tie were worn with long trousers on formal occasions and the bush jacket with shorts/trousers were the more normal (shirts and shorts were the normal working dress).
The real 'bees knees' was the all white No: 6A. High neck jacket, mess dress rank boards BUT black shoes - not white as the RN did. Worn by stn cdrs, ADCs and the like.
KD still worn where appropriate, although since most of our overseas presence is now centred in operational areas, it is probably worn by significantly fewer people than is combats.
Going back to the original Thread - between 1 Jan 50 and 31 Dec 53, the RAF lost 157 - YES - 157 Harvards in accidents and this was complemented by significant losses to Oxfords as well.
Drifting again: since VE-Day, the RAF has lost 9300 aircraft in accidents and over 6000 fatal casualties in those accidents. The worst in human terms is the Hercules off Pisa in '71 and the Hastings at Abingdon in '65. Stark reminder of how things used to be.
Old Duffer