What characteristic did Mr. Sewallis Evelyn Shirley focus on establishing to separate the Flat-Coat from another existing retriever?

Answer

Its distinction from the Curly-Coated Retriever

Shirley actively worked to establish clear defining characteristics intended to differentiate this new breed from its close relative, the Curly-Coated Retriever.

What characteristic did Mr. Sewallis Evelyn Shirley focus on establishing to separate the Flat-Coat from another existing retriever?
Dogbreedlineagecoatretriever