UK AIP ENR 1.1.1. reckons:
The initial call changing radio frequency shall contain only the aircraft identification and flight level. Any subsequent report shall contain aircraft identification, position and time except as provided for in respect of helicopter operations in the areas specified in paragraph 1.1 (d) above.
Note. When changing frequency between any of the London Control, Scottish Control or Manchester Control Centres, pilots are required to state their callsign and Flight Level/Altitudes only (plus any other details when specifically instructed by ATC). When the aircraft is in level flight but cleared to another FL/Alt, both FL/Alt should be passed. Similarly, when the aircraft is not in level flight, the pilot should state the FL/Alt through which the aircraft is passing and the FL/Alt to which it is cleared.
Mr AIP is usually correct, in my experience!
Doesn't really solve the phraseology issue, but a suppose CAP 413 would do that!
Rgds,
Cuban_8