WorkingHard
Re your "thorny question of ROCAS"
From MATS Pt.1 :
"The Manual of Air Traffic Services contains instructions and guidance for controllers providing Air Traffic Services to cater for both routine and many emergency situations. However, nothing in this manual prevents controllers from using their own discretion and initiative in response to unusual circumstances, which may not be covered by the procedures herein."
In other words, just because it's not covered in MATS 1, doesn't mean the ATCO is wrong to say it.
If it concerns you so much, why not write to the SRG Head of ATC Investigations and ask what the view would be of an ATCO who hadn't said ROCAS to a pilot who then infringed ? (I don't mean one who asked for a clearance but was told to wait). I suspect a dim one !
I assume you are aware that any pilot refused entry into CAS can notify DAP, who will request an explanation from the Unit ?