What sort of rear lights do you have? It was a complicated time, my 1949 Light 15 would originally have had a single round “pork pie” light mounted over the number plate on the offside, early Morris Minors had the same setup but not sure it would be acceptable today. This was soon changed to two triangular rear lights, Lucas 471, the same as Morris Minors and Triumph TR2s and available in glass or plastic. Then in 1954 the regulations changed again and reflectors were required, as a temporary measure Morris and Triumph added separate reflectors before Lucas brought out the Lucas 549 unit with integral reflectors but only available in plastic and very common on British cars, my Citroen has these.
Cheers
Richard