He matriculated at Christ Church, Oxford in 1790, receiving his BA in 1795 and his MA in 1796.
[1] In 1798, his brother John Dawnay, 5th Viscount Downe presented William to the rectories of Sessay and Thormanby.
Both of these livings are in North Yorkshire, and were in the patronage of the Dawnays, as was Ashwell, Rutland, to which he was presented by his brother in 1803.
[2] On 6 June 1811,[1] William married Lydia Heathcote daughter of John Heathcote of Connington Castle, by whom he had three children:[2] Dawnay inherited Beningbrough Hall, Yorkshire, in 1827, upon the death of Margaret Earle,[3] mother of his school friend at Eton.
[2] Downe died at Torquay in 1846 and was succeeded by his eldest son William Henry.