Expedite,
As a BB based pilot (trainer), I find the logic of our 'BIG' colleagues interpretation of the rules somewhat stupid!!
Certainly having ONLY been given a lateral clearance change then we have NO right to change the vertical clearance. Please do be aware though, as 10W says that when cleared lower, we CAN ignore the earlier descent restriction unless you restate it.
Personally I always operate to it, and teach others to do the same, as I appreciate that in your minds your expecting us to anyhow, and it's better safe than sorry.
There have been many occasions when you could get caught out however if people applied the letter of the law. The number of times I've been released clean by LMS at say FL260, cleared FL200 when ready level by HEMEL. On first contact with COWLY/WELIN have been cleared say FL180. I have the right now to ignore completely my HEMEL restriction - I don't, but please do be aware that someone may! As always the time it'll happen is when you really don't want it to :-)
Whilst with you, is there really any ATC value in us BB outbounds having to work CAPITAL outbound? So far I've only ever been on freq a matter of seconds ( climb FL220, and chucked to LMS). From our point of view it's a 'pain' but happy to be educated in a reason for it.
Regards
MidOcean