Brewer's: Deva's Vale
The valley of the river Dee or Deva, in Cheshire, celebrated for its pastures and dairy produce.
He chose a farm in Deva's vale, Where his long alleys peeped upon the main.
Thomson: Castle of Indolence, canto ii.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894