From my WW2 RAF reenacting days....
Brown suede type with front zip, lambskin lining and moulded soles were issued to all BC crews.
Black 'escape boots' ('43 pattern) were issued to some BC crews likley to be shot down over enemy territory. Consisting of a stout leather military shoe with attached black suede gaiter, sheepskin lining, side zip and escape knife in a pouch on r/h leg inner lining. The gaiters, once detached with said knife, could be zipped together to form a serviceable body warmer.The shoes, once scuffed and muddied, would pass as workman's wear, I have no idea how one would pass off the heated Sidcot suit as one attempted evasion, but at least cross-country trekking would be possible with one's silk escape map and compass.....
Black leather flying boots, shorter than the escape boots, were issued to most other pilots, especially FC.
No prizes for guessing which type I have - they're extremely comfortable to stomp around in all day!
Ripline