Most Alvis cars were delivered with Lucas products to light the way and power the sparks. Some had elegant Marchal headlamps. The Three Litre models were Lucas equipped, except for some of the Swiss bodied versions by Graber. He fitted Marchal headlamps, which are slightly larger in diameter than the Lucas ones and look better for it. At the back, Graber was able to use the rather elegant Lucas light units first fitted to the Rolls-Royce Silver Cloud.
He continued to use them while RR were building the Alvis Park Ward bodies from 1958 with a different Lucas unit, previously seen on Humbers, Aston Martins and Continental Bentleys. At some point, before the Silver Cloud III received larger units, whether by choice or necessity, Graber restyled the car to include a new set of lights which were also made in the UK.
The make is Yeadon, and was used as side markers and for trailers. The red lens came in two types, one with a reflector and the other plain like the amber one.
If you know a source of such lenses, please leave a reply.
Alvis Archive 
Have you tried Historic Car Parts of Macclesfield? There stuff is mostly British Leyland stock from the ’50s and ’60s but they may have something useful.
Great stuff, but has anyone any idea where to find the flat dimpled glass used for Rotax lamps in the 1920s?