Good question, but they specifically state;
"For class 3,4,5 and 7 vehicles, the defect ‘Light source and lamp not compatible’ only applies to vehicles first used on or after 1 April 1986.
Should a vehicle be presented for an MOT test with conversions before 1 April 1986 they must not be failed with immediate effect.
Vehicles presented with converted halogen headlamp units first used on or after 1 April 1986 will continue to be failed."
So it's down to interpretation by the tester perhaps. Time will tell.
