|click on the image for a larger view|
The watch has a 15 jewel Ehrhardt movement - probably a 1906 series but I have yet to take the dial off - it was made for the British Military during WWI (note the broad arrow property mark below the serial number) but was one of many made by the company that were never delivered and then put into silver cases and sold to the public, this one hallmarked by Ehrhardt in 1921.
It was advertised as "in very good condition and working" and "the watch will run the full length of its wind but does run slow I think it needs a service, the watch sum [sic] time stops I shake it and it starts again".
It should be restorable but will take longer than it should.
WD40 is great stuff - but not on watches!