CAP 413 says
Radiotelephony provides the means by which pilots of aircraft and ground
personnel communicate with each other. To ensure communications are
clear and fully understood it is of vital importance that transmissions by
radiotelephony should comply with internationally agreed procedures and
phraseology
An interesting comment. Where is this Internationally Agreed phraseology published? Is it ICAO Doc 9432 which was a copy of CAP413 Edition 1? And of course is the basis for the EASA Comms Exam. CAP 413 Edition 21 has moved on a bit, but is unique to the UK, and has never been Internationally Agreed.