Bailey Unicorn Roof Light.

Have just discovered that we've "lost" the dome from the top of our Roof Light in our shower compartment. Don't know how or when that occurred although it was very windy when we were up at White Water, but I doubt that it was strong enough to blow it off. Perhaps we didn't close it properly prior to towing down there, although we are sure that we did, and it blew off en route. Does anyone know where I can obtain a replacement? As we are away on tour in East Yorkshire at the moment a the name of a dealership that may have one would be very welcome.