EGGX clearances delivered via VHF, HF or ORCA/ACARS will stress any change from the profile specified in the FPL/request as a standard procedure.
The clearance issued in the T16 example would have been:
"Shanwick clears Bigjet123 to Tenerife South with a level change/change of flight level via Omoko, Gonan, 40 North 16 West, Navix. From overhead Omoko maintain flight level 360, mach decimal ??"
It may have also been...
"Bigjet123, Shanwick"
"Bigjet123, go ahead"
"Unable your requested level, Shanwick clears Bigjet123 to Tenerife South via..."
(I'd have to look it up in the EGGX MATS Part 2 for the exact wording)
Can't speak for others (LPPO in this case) but it's how EGGX does it. Sounds as though it does as intended in giving you a heads-up
If you feel strongly enough, get your head of safety to write to LPPO and suggest that they consider adopting a similar procedure.
PS - If the clearance comes to you via HF, you're talking to a Shannon Aeradio ("Shanwick Radio") Radio Officer at Ballygirreen, (Co. Clare), who acts as the (HF) voice of Shanwick ATC. If the clearance comes to you via VHF, you're talking to an Air Traffic Services Assistant, acting as a Clearance Delivery Officer, who is the (VHF) voice of the Shanwick Controllers (Planners); these being located at the Prestwick Centre, (Ayrshire). If your clearance arrives via ORCA/ACARS, then it has been sent directly from the Planning Controller's work station. You'll never 'speak' to a Shanwick Controller. (Probably a good thing
)