The 1939 print of the
Vincent Annual Sales Leaflet shows a Meteor with a rear light that look like a 35E but it is not possible to see the rear light on the illustration of the Comet (both have pillion seats)
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The
1939 Miller Spare Parts List offers two tail lamps, both complete with bulb and cable - the 35E (1 shilling& 9 pence)and also the 39E (3 shillings & 6 pence) - the difference being the 39E is "Designed specially to illuminate large number plate" - however the List shows the same illustration (R121) for both lamps (and spare bulb holder - spring & pad)
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From the pictures Davidd uploaded it would appear some machines had the 39E even if they were twice the price of the 35E?
There was also a stop lamp available (the 29E) - "similar in design to the 39E. Supplies complete with two bulbs, cables and switch for brake pedal" for 9 shillings & 6 pence! There is of course no reference to a stop light being available in the 1939 catalogue
I find it interesting that all of the photographs and illustrations I have seen show no protrusion of a convex headlamp glass
SteveE