In regard to the origin of the Hackney, like that of most breeds of large stock, it is lost in the mists of obscurity, but it is held that they are probably the oldest variety of light-legged English horses.
However, a good deal is known about the background of the Hackney and it is reported that they are the descendants of the famous trotting horses of the 18th and 19th century of which there were two regional types, the Yorkshire and the Norfolk Roadster. Although Yorkshire and Norfolk horses share a common ancestry, the two did to a certain extend develop recognizable characteristics.
Possibly during the transition from Roadster to Hackneys or even earlier, the Hackney mane was synonymous with the name Roadster. There is abundant documentary evidence to support the statement, such as this quotation from John Lawrence's book published in 1809 in Britain and entitled, " The Delineation of the Horse in all its Varieties." Our present varieties of the horse, and their denominations are as follows: The Racer, Race Horse; the Hack, Hackney, Roadster, Road horse of Chapman's horse; a cloddy compact horse, or gelding of this description is now and the styled a cob; the lady's horse a Pad; the coach horse, chariot and Curricle Horse; Gig horse or Chase horse; the Machiner or Post hack; the cart and dray horse; Galloway and ponies. "The old French word "Hacquenee" has existed in England since the Normans settled there in the 11th Century, and has been mentioned is scripts in 1350.
The name "Hacquenee" gradually changed into Hackney and has come to denote a general purpose horse, and the vehicles which he pulls. In England the word was specifically applied to a type of harness horse midway between the light and heavy types. It was applied as the breed name when the Hackney Studbook Society was formed, and spelled afterwards with a capital letter to distinguish it from the old usage.