I am sure there is someone more knowledgeable than me who may tell you if I am right or wrong but I have always thought that the show cocker originated from the working cocker. So, if you think about it, all show cockers have worker in their pedigree if you look back far enough
I am talking many,many,many generations back, of course.
Perhaps your breeder didn't feel they needed to inform you as predominantly the pedigree is show type and the puppy displays all the characteristics of a show cocker.
To become a F.T. Ch, a dog has to be very biddable and have brains so to me that is a desirable trait to inherit.
In theory, there is no reason why working type and show type cocker can not be bred together as they can both be K.C. registered cocker spaniels. It is just that serious breeders tend to keep the two types separate.