Breeding to SOP

[JedJackson]

This is a quote about Australorps and their creation: "The Australians were very practical poultry breeders, and so with egg production as a singular goal, they made outcrosses to Minorca, White Leghorn, and Langshan chickens – even as William Cook had in the creation of the Orpington. The end result was an excellent production chicken, but one which little resembled Orpingtons as bred in other countries."

Here is a quote about the creation of Orpington varieties:
"William Cook enjoyed a rare commodity – success – and his fortunes grew. But it is not his entrepreneurial spirit that is to be celebrated, but his skill in breeding. Mr. Cook focused his breeding efforts on developing the body and productive traits of his poultry; in the process many birds came as they might in color pattern. Thus Mr. Cook had the bright idea to create many varieties of his Orpington chickens. He first introduced the Black, and then the White Orpington, the Buff, the Jubilee [Speckled], and the Spangled [Mottled]. His son-in-law, A.C. Gilbert, created the Blue and the Cuckoo Orpingtons."

Both quotes are from the American Livestock conservancy pages.

As far as Cook goes, it was widely believed that he used other varieties to create his other colors. Lincolnshire buffs, an early meat breed created by crossing red Dorkings with buff Cochins, were rolled into and became buff Orpingtons in the same way that the early Dominiques were rolled into and standardized as barred Plymouth rocks, with just the smaller, rosecombed birds being allowed to continue as standardized Dominiques. In fact all the Plymouth rock varieties have different ancestry than the original barred birds, with the exception of white rocks, which were color sports of the original variety.

 

[TomNY]

Cook also created a rose-combed version of each of his five colors. RC Blacks, Whites and Buffs enjoyed some early popularity but RC Diamond Jubilee and Spangled never caught on.

 

[TomNY]

Cook did not create the other colors of Orpington. He only created Black to which were developed into buff in area where common egg layers were buff. Other varieties were added later and not by Cook. The original Black were sent to Australia where they were selectively bred, without addition of external breeds, to become the better utility breed Australorp. This would be the same as RIR that was selectively bred to become the better utility breed New Hampshire.

To the original OP's question- Yes, any bird or breed can be used to obtain another breed. If it breeds true and matches the description of the intended breed then it is that breed. The adage if it looks and quacks like a duck then it is a duck comes to mind.

Check your facts. He created Blacks first but also created Whites, Buffs, Diamond Jubilee and Spangled. He also created a Rose-Comb variety of these five colors.