I haven't been on the forum for a while as I've been a bit snowed under with work, but I just discovered this thread.
I've done a fair bit of research over the years on the history of the Sunbeam marque. There's a link to my website somewhere on this message if you want to read in more detail.
Anyway, John Marston owned a company that made a diverse range of products. Along the way he started making bicycles under the Sunbeam name. From bicycles, Sunbeam went on to make cars and motorcycles.
Over time the various branches were split off and became independent of each other. The car division became a separate company very early on -soon after the turn of the century - but John Marston remained at the helm until his death in, errm, without looking it up, about 1918. The car company then merged with the Anglo-French Darracq/Talbot combine.
Sunbeam Talbot Darracq spent huge sums on motorsport, not only setting land speed records, but winning grands prix, placing at Le Mans, etc. Sunbeam was probably Britains most successful racing car constructor until the depression brought it to it's knees.
Rootes stepped in to save it, planning on making Sunbeam their top of the line make - above Humber, aimed at Daimler, Rolls-Royce, etc. Somewhere along the line they decided they couldn't do this profitably, so instead Sunbeam was merged with Talbot, whose British arm they had also bought, and the cars became Sunbeam-Talbots. Eventually the Talbot bit was dropped and they reverted back to being Sunbeams again.
(Rootes did not buy the French arm of Talbot. This later became part of Simca. Chrysler bought Rootes and Simca and merged them together bringing the two halves of Talbot together again!! Then when Chrysler sold Rootes/Simca to Peugeot, the Talbot marque was revived briefly again.)
The bicycle and motorcycle divisions were taken over by ICI initially. ICI sold the motorcycle arm to BSA later on. BSA built bikes under the Sunbeam marque for many years, but killed them off in the '60s. The last model was the BSA Sunbeam motor scooter.
ICI eventually sold the bicycle arm to Raleigh. Raleigh used the brand up into the 70s, and I think it died sometime around then.
Whew!