Found on another forum law regarding the above:- "IT is not acceptable to convert a headlamp approved for use with a halogen filament bulb to use a Xenon (HID) gas discharge bulb. The only acceptable way of converting is to replace the headlamp with one approved for gas discharge bulbs. Such headlamps will be approved to UNECE Regulation 98 and 'E' marked. If headlamps approved to UNECE Regulation 98 are retro-fitted, they must be self levelling (as part of the headlamp system, or via self-levelling suspension), and headlamp washers must be installed. Under the road traffic act 1988, it is an offence to fit or use parts which are not legal." Wondered if it would fail an MOT, or would they know?