|An unsigned Benson "Bank" type|
cleaned with metal polish.
(Click for a larger view)
This movement is a recently restored unsigned J.W. Benson "Bank" type which I believe to have been made by P & A Guye as explained here.
At some time in the past, probably fairly recently, metal polish has been used to clean the top plate, this has removed the gilt finish.
Although it looks rather better than the picture would suggest the top plate no longer matches the balance cock or the bottom plate and the value of the watch has been substantially reduced.
You have been warned!