Took the other bike for an MOT last week and the tester pointed at a bit of paper explaining HID. It seemed that in themselves they are not illegal but the beam they cast could be cause for an MOT failure. As the top of the beam must be flat, most hid's are round, on a normal bulb there's that silver bit on the top that makes it flat. Even thought the lens is E makred.
So the bike failed the mot, luckily 10 minute job to swap out and passed...
Trying to find a HID bulb that casts a flat beam.
hth