Only necessary if your bike has a pillion seat. Obviously. ;)

I seem to have become an MOT saddo all of a sudden. :yawn:

I was led to believe that certain items that are optional must work, but only if they are fitted. So if you had front facing fog lamps on a car and they didn't work then it would fail - however if you removed them then it would pass.... perhaps the same applies to the rear number plate light. I've noticed a lot of companies that sell after market under trays always supplied new tail lights with number plate lights fitted.

number plate light is law so the police can see your number plate in the dark