DXL 374, part of the Baxter Collection.
The chain guard is a modified Morris 1000 wheel cap. No spring washers have been used on the bike, but it remains mechanically sound.
This one is in the Wirral museum located in the Town Hall at Birkenhead Woodside. The rest of the collection is in the the fantastic Wirral Transport Museum
"Frank Parkyn, cyclemaker, started building motorcycles at his Granville Street factory in the early 1900's. He started producing Olympic bicycles in Green Lane in the early 1880's and moved to Granville Street in 1896. His motorcycles were powered by M.M."
...in 1902 they began producing French Darracq models under license and selling them under the brand name "Opel-Darracq." They were Opel bodies mounted on a Darracq chassis and powered by a 2-cylinder engine. The first Opel motorcycle was also built.