You must have been submitting this as I wrote an answer to your other query.
WDS was the common frame number prefix used by Excelsior for their 125 and 197 Villiers powered models between 1951-1954. At that stage they made both Villiers powered machines and machines powered by their own two-stroke engines. Mainly the Villiers powered machines have survived as the Excelsior engines are hard to get spares for and were no better than their Villiers equivalent anyway. Villiers spares are comparitively plentiful.
I have no information to identify exactly what WDS numbers refer to what year.
Cheers,
