bookworm,
As you appear to understand; "... a pilot shall not change level or level band without first advising and obtaining a response from the controller, as the aircraft may be co-ordinated ... without recourse to the pilot." (Traffic Service, MATS Part1 and CAP 774.
However, I've yet to meet anyone who doesn't ask or advise the pilot about the co-ordination before imposing it. Technically Brize didn't do anything wrong though.
Regards, ADIS