Just had a couple of the festoon ones delivered for the rear number plate, but as it was persisting down outside (and bloody cold) thought I would leave that for another day.
Was still interested to see exactly what difference there would be, so I swapped out the central interior light for one of these LED jobbies, and could believe the difference. Never noticed how yellow the old filament ones were. Here's a couple of pics:
Deffo going to have to do them all now