Originally Posted by PeterLYoung

Just acquired another Sunbeam at a bike jumble. looks all to be original except for the SA Shifter as it is a BSA built Sunbeam and has a BSA 3 Speed. It has flat North Road bars and Sunbeams own Centre-pull Brakes. Also it has the iconic 'Little Oil Bath" gear-case.
It is in rideable condition and will get the oily rag treatment plus all bearings stripped, cleaned, lubed & adjusted plus the cables need lubrication so they free up fully, they do operate the brakes but are a bit stiff.
The serial number of S48571 compares to VCC Library verified purchases to a 1949 S48161 so putting it at 1949/50. I think it is a W3 Wayfarer. These Sunbeams are unique in the the Chain-case forms/replaces the drive side Chain-stay tube. they bath the chain permanently in oil prolonging the life of the drive components.