Possibly because promotion is single-service, and no-one gets promoted from a "gucci" / "crunchy" joint job if they've out joint requirements ahead of their single service's interests.
Q. How many RN types would have gotten a tick from a promotion board for recommending binning the CVF programme as it was unafforable?
A. About the same as the number of RAF types who recommended slimming down Typhoon costings in the last decade plus...
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