"Frankly who gives a t*ss if RT phrasology is EXACTLY in accordance with CAP413? So long as its clear, concise, and unambiguous, then who cares."
The reason CAP 413 is there, is to provide pilots with standardised; clear, concise and unambiguous phrases. Its also there so that pilots whose mother tongue is not English can learn and understand those phrases.
Because we speak English and can cope with a wide range of non standard phraseology does not help the foreign pilot.
Unfortunately, before long there is going to be a major aircraft accident because some pilots don't give a t*ss. Numerous working groups have predicted this and are continually raising issues with current RT standards.
As the principal English speaking nation we should set an example by doing it by the book. 90% of RT is learned by copying others.
If an ATCO gets it wrong he is suspended. If a pilot gets it wrong he flies again the same day!