Given that virtually every other piece of military clothing used in the film was sourced from RAF surplus (like Star Wars, due to availability where it was filmed),, it's probably more likely that the lace-up sections came from 1960s/70s RAF G trousers and jerkins (worn by EE Lightning and Phantom FG1/FGR2 pilots). Here's an example of the same lace-up sections on a set of RAF G trousers (the laces are normally hidden by expandable panels that the laces thread through):
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The white cooling suit seen hanging up in the Narcissus' suit locker was an RAF Mk2C air ventilation suit worn under the Lightning partial pressure suit (wiith an RAF Taylor half pressure helmet above it)
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It was also used as the base for he 1970s Cybermen costume:
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It was also used in Blake's 7, worn by David Bowie in the Ashes To Ashes video and by Kate Bush in the video for The Dreaming.