Unlike the German forces in Russia who died in hundreds of thousands because of inadequate clothing, the clothing which the RAF equipment Brand supplied to its aircrews to combat the cold at high level was of the highest quality. In 1944, high level meant 20-25000 feet. Aircrews were provided with (apart from the normal clothing) long sleeved cotton vest and long cotton pants (Long Johns). The material was white and softer than the usual oatmeal wartime clothing. The word Thermal was a meteorological term and it was 30 or so years later before the term was used to describe warm clothing.

After the underwear, when preparing for a high level mission, some wore unapproved civilian shirts or another vest (currently called T shirt). RAF shirts (all ranks) had all separate collars. Unfortunately, the collar attached shirt was not in vogue. The collars were attached to shirts by "metal" collar studs at the front of the neck and at the back, so were not a favoured attachment for flying, being restrictive and uncomfortable.
Scarves were an acceptable alternative and were usually silk and carried some emotional association as presents from ones Mother, or sweetheart. No matter how colorful, no remarks were ever passed. They were an accepted divergence from uniform flying kit.
Usually, over the shirt went the normal battledress top, though not always. Some preferred the extra long white pullover like a fisherman's jersey over the battledress blouse and some under. Generally, there was complete diversity of uniform at the Briefing stage of an operational flight . The only caveat seemed to be that if service uniform only was worn, then it should be correct. Collars, when off duty, were often starched and if required to look particularly smart, would be finished by rubbing with a candle ; it also meant that it was good for an extra day or two.. Only idiots would fly in their best uniforms with a starched collar, but they were some who did, but not so much idiotic as it sounds. If one was due for leave immediately after an OP and already had their signed and stamped leave pass, ration cards and rail warrants etc…the real enthusiast would leave his clean collar and black tie in his locker and could be seen disappearing like a scalded cat with his gas-mask as soon as he was de-briefed, to catch the earliest possible train. The desire to get back to one's family and reality was very strong.

The next item of flying clothing would be the very thick and coarse woollen socks over battledress trousers. The socks looked like hand-knitted and went over normal socks They could be pulled up almost to the thigh or turned down. Elegance was not a consideration.
There were some sights in the locker dressing room but nobody cared.
Over the uniform with the long vest and Johns under, went the electrically heated suit, in brown soft shiny material with electric elements covering most of the body including the most important electrically heated gloves. Before these, one put on a pair of long silk type gloves, a material called cellanese.The penultimate electric gloves had metal studs connected to the main supply at the wrist. The gloves had an electrical element down each finger and thumb and when they worked, they were warm and comfortable, but could be known to get unbearably hot. It was not the best of situation when bombing over a flack intense target or being attacked by a German FW 190 or Ju 88, to have an electric fire under one's armpits. The electric umbilical connector came through a slit in the outer clothing to finally connect when inside the turret.
However, there was more clothing. The electrically heated suit was not the last item of flying clothing. Next came a gaberdine flying suit well pocketed and zipped with a fur collar ; the latter was useful as the rear turret was an extremely draughty place, so all this with the Mae West on top and finally the parachute harness, the last piece being the soft leather gloves over the other two hand items. The air gunners by now looking somewhat like Michelin men walked like waddling geese to the crew coaches to take them to the aeroplanes.

There was a short lived innovation in Air Gunners clothing called a Buoyancy Suit. This was a bulky double material filled with kapok (goose feathers) to provide warmth and would keep one afloat in the sea (so it was said) without an additional life jacket. A good James Bond type idea on paper (there was an acute shortage of volunteers to try it out) but it was unpopular as it was so bulky and allowed even less room to move that it caused severe discomfort and cramp.

Sharp readers may wonder why the Mae West was under the parachute harness. I remember now I was awake the day they told us about bailing out over water and how if you didn't do it properly you could drown if the parachute came down on top of you or even suffocate under it if you had a choice. The trick was to inflate the life jacket as you approached the water, turn the central ring on the front of the harness and about ten feet before you hit the water, hit it sharply with your clenched fist and you should fall into the oggin with an inflated Mae West and no parachute. It sounded a neat trick, so we all made a note in our books.

The "Office" aircrew at the front end, Pilot, navigator, Wop etc. with their "central heating" did not require the bulky additional clothing which the Air Gunners needed, so flying boots and an outer sheepskin jacket were usually sufficient for them. This was because the front part of the fuselage in the cockpit area received the constant heated warm air blown from the inboard engines (The heat controls for the front crew compartments were on each side of the fuselage just forward of the front spar with adjustable louvers operated as needed by the flight engineer).
The bomb-aimer was the exception if he elected to spend more time in the prone position in the nose of the aircraft which he occupied for bomb aiming and visual "map reading".
Map reading at night ? - Map reading was an essential aid to navigation and at night, salient features of towns even with black-out restrictions, coast lines, rivers, lakes and canals could all be clearly identified on a moonlit night. It could also be very cold in the front gun turret, which was also part of a bomb aimer's responsibility when needed.

Of the two gunner positions, the rear gunner was by far in the coldest position, and condensation from breathing often froze around the mouth and oxygen mask. Even at 20 000 feet plus, it was possible to remove the mask for a few seconds to clear the ice and condensation from the face mask. Goggles were issued but were an incumbrance and a further clear vision impediment. It happened that sometimes the eye tear ducts also became frozen. But the tiny tear drop icicles were hard to remove with the several pairs of gloves. It was too dangerous to remove them in case you weren't able to get them on again. The bottom half of the Middle Upper turret was open into the fuselage so some heat from the front of the cockpit got into and around the gunners leg, but the rear gunner when he was bundled up and squeezed himself into position closed to rear turret doors and he became isolated from any heat source in the cockpit.

T.J. Maxwell answers my question about personal protection when over a target.

- The RAF crews wouldn't have known what to do with a flak jacket as we never had such and as I said the only bit of armoured plating in the Lancaster or for that matter in any RAF aeroplane was a piece of half inch steel plate immediately behind the pilot .Tthat was all. We wore only leather helmets and perhaps in ignorance we thought we were well looked after . All that extra weight in heavier ammunition , Flak suits , and armoured plating etc. was allocated to a few extra bombs by the RAF