Sparto origins

I have tried a few times locate the origin of the "Limp Dick," "Limp Sausage"...(whatelse has it been called) the chopper tail lamp...

The Sparto was made in England... for what make or model? Was it ever a stock piece of equipment? I always figured '50s or maybe earlier.

And what about the lens...glass or plastic....flat cup or domed...with a metal door or collar? Did it require the use of a gasket on the fender?

Has anyone researched this at any time?
I have seen pages of an early Superior catalog with references to replacement lens, I think.
I have asked a few folks but never learned anything substantive.

Hurtn, for sure

The first ones were wing lights made in the late 1920's to fit the curve of the front a airplane wing ,same curve as a bike.Made by GRIMES MFG.. Hard ta believe but they have a museum for them in Urbana Ohio.YOUR TAX MONEY AT WORK !!!The first ones used on a stock bike were the Crocker with the glass beehive lens held with a snapring.I think the sparto came out in the late 50's they had a cheap flat front plastic lens held with a small screw the lens was famous for falling into the street.Sparto was aftermarket and had a rubber under it.

Here , we all use to call it "dog dick"...

I just named my puppy SPARTO Ya it's French Poodle