High Altitude Flying Equipment
I don't know what Canberra crews might have worn at High altitude in the 50s.
When I flew the PR9 we went to RAF Upwood to be fitted with our kit which consisted of a sort of pressure suit comprising a G suit and a pressure jerkin, for the body and legs, and a Taylor partial pressure helmet. This had a small 'Hatch' in the front thru which one could eat very small sandwiches and snax but this was difficult as the hatch was more aligned with the end of one's chin than one's mouth! There was also a hot weather option of an air ventilated suit to worn underneath all the kit and also an air vent skull cap to wear next to the skin and under the helmet.