Stanley
Cash Again & Again (UK CAA) have always reserved the right to use other publications in addition to CAPs but rarely do. I have been a TKI for 20 years including transferring from CAA to JAA then EASA and understand your frustration & agree with your comments. Unfortunately the system has stunk for years and it doesn't get any better, it's a licence to print money asking poor, irrelevant, totally out of date questions that does nothing to improve flight safety.
It will be interesting to see how the new Jeppesen questions are introduced in a couple of weeks as every time they introduce new material there is screw up (but it's not their fault of course).