Last night I noticed there was a light out on the rear passenger's side so investigated today. Seems like there's no current coming to the rear tail light and number plate light. The one on the other side works so rather than try to get the loom out and unwrap it I put a wire in a bit of corrugated tubing from the side that does work to the side that doesn't. All working as it should now. The brake lights and indicators were unaffected so I left them alone. The lights are all LEDs so the load on the good side will be minimal.