It would seem that prior to 1977 there was no fitness test for servicewomen. In 1977 a simple step test was introduced.I’d be genuinely surprised if the move from boots to trainers for the BFT has anything to do with the end of the WRAC. More related to a massive rise in lower limb injuries in the mid 80s to 90s coincident with the introduction of the BCH, later followed by the BCA and also the replacement of the black / white dap by the silver shadow trainer.
interestingly, I have started wearing barefoot trainers - remarkably similar to running the APFA around Old College and double endurance on Barossa in white daps.
This takes forever to load but quite interesting.