D'Oyly is a Norman French name, from the place name Ouilly near Lisieux in pays d'Auge, present Calvados département in Normandy.
The Domesday Book records that by 1086 D'Oyly and d'Ivry held a number of manors either partitioned between the two of them or administered in common.
[citation needed] The latter was during the economic decline that Oxford experienced between 1066 and 1086; however, it is noted that Robert's own properties suffered as much waste in this period.
Robert was appointed High Sheriff of Oxfordshire and ordered the construction of many parts of Oxford, some of which still survive today.
This now forms the major route between the city centre and the south, and the crossing point is near St Aldate's over Folly Bridge.
D'Oyly also owned a considerable amount of land in Oxfordshire and in Oxford itself recorded in the Domesday Book of 1086: With his wife Ealdgyth he had a daughter and heiress Maud who first married Miles Crispin (d. 1107), Lord of Wallingford, and afterwards Brien FitzCount, lord of Burgavennu (the faithful ally of the Empress Matilda), but leaving no issue, was succeeded by Nigel D'Oyly, her uncle, who was constable to William Rufus and Baron of Hocknorton.