rear light

[Colin F]

This is the information I have on it..

Replica Wipac rear lamp. As fitted to BSA Bantam, C10L, Triumph T20B Super Cub and Ariel Colt models, AJS/Matchless lightweights, Francis Barnett, as well as Sunbeam models.
This rear lamp was also known as Series 143 and Series 143b, when the unit was fitted with a stop and tail lamp in the mid 1960's, under part number S3611.
Often called the Sabrina lamp

[T]

The S 179 ? it should be like this ( on my '59 model 14 AJS ) - - It's a horrible thing screw-in side bulbs , and the centre single filament one has to be a small globe type as a normal bulb won't fit ! deep joy . Cost me ten bob - I was robbed

[Phamiltoneddy]

The eBay advertisement in the link posted by borrowashboy misdescribes the Wipac light in the photo as S179. In fact, it's an S3611 "Sabrina" unit that was never fitted as original equipment to AJS and Matchless lightweights. Incidentally, the "Sabrina" light was so named becuse its twin promontories called to mind a particularly well-endowed late 1950s starlet of that name.