5.—(1) If any alteration is made to an external doorway of an exempted vehicle or to the door-operating mechanism of such a doorway then the authorisation to use that vehicle even though that doorway does not have handrails which conform with regulation 11(1)(a) shall cease to have effect in relation to that vehicle.
(2) If any alteration is made to the layout of the seats or handrails inside an exempted vehicle then the authorisation to use that vehicle even though such handrails do not conform with regulation 11(1)(b) shall cease to have effect in relation to that vehicle.