This section is from the book "British Dogs, Their Points, Selection, And Show Preparation", by W. D. Drury. Also available from Amazon: British Dogs: Their Points, Selection And Show Preparation.
In considering the following descriptions of the principal varieties among British Spaniels, it must be borne in mind that, with the possible exception of the Clumber, they are all ramifications from the same stem. So close, indeed, is the kinship between them that they can be interbred with advantage to preserve vigour of constitution without jeopardizing the various types. An illustration of this is the crossing of the English with the Welsh Springer: those puppies that are liver-and-white or black-and-white follow the shape of the English breed, while the red-and-whites present the undiminished type of the Welsh dog.
The same phenomenon has been noticed among Setters. In the same litter the blue-mottled pups will be found of one type, roughly resembling that of the English Springer, while the shorter-eared orange-and-whites have more affinity with his Cambrian cousin. This seems to confirm the notion of Blaine (1839) that the red-and-white Setters and Springers were originally distinct from the Spaniels of other colours, though themselves, of course, from the same stock.
There are several sub-varieties of the great Spaniel family that are not described in these pages, because, though capable of culture, they are at present too restricted in numbers, and not sufficiently defined, to merit special classification.