I read this recently:
'if the mobster has made up his mind and issued an edict that FTLs are wrong and should be used as a guide only'
The FTL's are as per the Operations Manual, not necessarily CAP371. The Operations Manual is approved by the 'Campaign Against Aviation', if it is said these FTL's are wrong then the Operations Manual needs amending, of course such an amendment will need to be approved by the CAA.
Until such time as the OM is amended then you should operate to what it dictates, it is not advisory, it is mandatory!
I'm not sure what an 'edict' is but if it's something that is intended to override the OM then surely it should be a 'Flight Crew Notice', which I believe should also be copied to the CAA.
I believe that such a Flight Crew Notice, or even an edict, cannot be issued by the Chief Executive, it needs to come from the Head of Flight Operations, if you have one!, or his deputy.
Not suggesting stupidity here but are you sure people are being rostered into discretion, I only say this because I have known commonplace confusion regarding such things as split-duties and FDP off-duty times. An FDP ends at final on-blocks, it's the DP that ends 15 or 30 minutes later, that's not discretion!