Are these on the same circuit by chance?

It seems both if these (all 4 bulbs) are not going. I've checked my no. Plate globes, and they don't look stuffed to me. Haven't yet attacked the reverses.. (Got to work out my way in).
I've checked obvious fuses, but seem ok.
Any ideas as to why? Other than bulbs obviously?

Possible fuse, pinched wire somewhere.

Looks like they use different fuses and if it was the fuse your front parking lights and tail lights would also be out since these share fuse 2 (10A - engine bay fuse box) with the licence plate light. Reverse lights run through fuse 5 (10A) in the fuse box inside the car (I think). I'd pull the licence plate globes and see if you've got power at the socket when park lights are on, ditto reverse lights when in reverse. Globes are cheap, if your fuses are ok I'd chuck in new ones to eliminate them or check each socket with a known-good bulb (or multimeter). If no go, check your looms and connectors.