For anyone else wanting to remove the switch, here's how:
1 Remove the cap from the pull switch
2 Undo the 8mm lock nut
3 Uscrew the barrel section of the switch
4 You can now see and remove the fascia plate retaining screw
5 The fascia complete with air vent can now be gently eased out from the dash
6 Compress the two lugs which retain the switch and ease it slide it out.
Simple!
Before refitting I taped the illuminated symbol plate to the back of the panel.
It's not "nephew-proof" but it makes the re-assembly a lot easier