One thing not specifically stated, but implicit in the designations, is that this equipment is pretty well 100% military (RAF, although as noted, FAA had their variations). RAF would have used such equipment (thinking of goggles and helmet in particular) until early/mid 1950s, when the first of the protective helmets were introduced (Mk.1) with the version with first up/down visor (Mk.1A) introduced shortly after that. There were also other tropical helmets introduced during WW2 which were made from "breathable" (cellular cotton weave) materials, but of somewhat similar pattern, some with neck flaps to protect the skin from sunburn. The Type G oxygen mask was gradually replaced by the superior Type H from about 1944/45, but the MK. VIII goggles were "timeless" and very similar ones were also manufactured for motorcycle riders for many years. "Electric" and "Gosport" microphone/telephone fittings could only be of use in one configuration or the other, at least so far as I know! The RAF Type C leather helmet was made in the tens of thousands, and no doubt many would have been "pensioned off" by the RAF in the 1950s and ended up with civilian pilots who liked (or had no choice!) flying in open-cockpit aeroplanes, in either configuration. The original natural rubber oxygen masks had the date of manufacture inherent in the rubber, and they tended to deteriorate with age, although the Type H mask seemed to have a fairly long life. However original Type G masks would by now be in a rather sad condition; I curated quite a collection at RNZAF Museum in 1990s/early 2000s, and all but one of the "G" type were getting pretty bad by then.
David D