Hi Byomarimba
Have a look at 
this link; as well as 
this one.  
Might just be a case of visual identify, then delve deeper - fortunately it seems Villiers, JAP, and BSA Matchless engines have similar condensors in many cases.  
Haven't had much to do with Villiers, so I can't comment on the farads.  
Edit, had a look at 
this other link, seems like the condensor is a m1750 model - no idea how to convert to Bosch though.  Anyway, most bosch would be complete different shape