Was able to spare a couple of hours this morning and relocated the number plate.
I didn't realise but the ADR requirements meant I have to mount a light on either side of the number plate approx 28mm away from it to be compliant.
So mounted the light brackets and extended the wiring to meet the exisiting
Thanks
@dagree &
@bigcol both suggestions were great, ended up sourcing the number plate wiring from underneath and tapped into that, (connected / soldered and heat shrink), was able to also keep the exisiting wiring in place in case I move it back
Tested it out before finishing it all off and thank goodness I had lights (based on my searching of the web it looked like the white was for earth (ground) and brown was power so hooked it up that way)
Finished off the cable runs and mounts
And finally the end product