The early facelift Omegas have a very annoying boot release 'feature'.
The boot cannot be 'popped' from the centre console button, unless the engine is off and ignition key removed.
Later facelifts had this feature removed.
To remove it yourself, simply detach the driver kick panel by undoing two Torx screws. (The bottom one is hidden under the sill cover. Lever off the VX logo plate on the sill cover to reveal the 4 Torx screws under it which retain the sill cover).
This reveals the 'Anti theft warning and central door locking control unit'
It has two plugs on its lower edge. A big one and a smaller 12 pin one. (On right in picture).
On the smaller plug, locate the two red wires.
Cut the thinner of the two red wires (Pin 3).
This is the 12v supply from the ignition switch 'W' contact when the key is in the lock. Without this supply, the remote boot release is always enabled.
Tape the bare cut end from the loom. (Shrink tube is better).
The finished result. An action shot of the boot 'popping'.
Edit. I must add a disclaimer here! There will be no delay on the button activating the lid, so it's possible to accidentally pop it. Especially important for estate owners.