As its name suggests, the Devon Rex originated in Devonshire, England. He is the result of the union between a curly-haired cat and a straight-haired cat owned by Beryl Cox. Thus was born Karlee, at the same time as the Cornish Rex began to develop.
Karlee was crossed with several subjects of this new breed. Newborn babies had straight, not curly hair. The gene in question was that of the Devon Rex.
The Devon Rex breed was not recognized until 1979.