The government have issued an update to MOT testers. (Annual car inspections for vehicles 3 or more years old)
As of 1 January 2021, section 4.1.4 of the MOT Inspection manual reads: “Existing halogen headlamp units should not be converted to be used with high intensity discharge (HID) or light emitting diode (LED) bulbs. If such a conversion has been done, you must fail the headlamp.” '
Before this, as long as the headlights worked and were aimed properly plus they had the correct beam pattern, a car would pass its MOT for that section.
Which meant that you could go on to the internet, find a seller overjoyed to take your cash while promising an ‘LED upgrade’ to your existing bulbs and voila!
Super-bright bulbs claimed to allow you see further but as a consequence blinded other motorists.