I have several pages from a book (title unknown) that has a brief history of the Devon House 1874, in fact that is the name of the chapter (pages 203-209).It also contains the followin on the Cawthra family:
"The Cawthra family, "the Astors of Canada," not only contributed much to the financial and social life of Toronto, they also built a number of very fine houses.
The Cawthras were an old Yorkshire family.Over the centuries their name was spelled in a variety of ways: de Caudrey, de Caudray, Cathra, Caudrew, Caudrey, Cawdra, Cawdray, Cawdrew, Cawdrey, Cawthera, Cawtherah, Cawtheray, Cawthray, Couthray, Coutheray, Kawdrey, Kawtherau, Kawtheran, and, in Scotland, Calder.
The ancestor of the Canadian Cawthras was Joseph Cawthra, who sometimes spelled his name "Cawthray."He was the son of Henry Cawthray and Mary Brown.Joseph was born in 1759 at Yeadon Hall, Yeadon, near Bradford in the parish of Guiseley.In 1781 he married Mary Turnpenny.There were six sons and three daughters, but only three sons and one daughter survived to accompany their parents to Upper Canada.They arrived in York in 1803, having stayed briefly in Scotland and New York before deciding to settle in Canada.Grace, their daughter, married Alexander Lege, but died without children.The sons - Henry (whose twin brother Joseph had died in England) died unmarried in 1854; William died childless; and John.Of Joeseph's nine children only John had a family.Today's Canadian Cawthras are all descended from John, son of Joseph and Mary."
I sincerely hope that this information will be of some use to family researchers.