Robert was the son of Walter D'Oyly and elder brother to Nigel D'Oyly. D'Oyly is a Norman French name, from the place name Ouilly near Lisieux in pays d'Auge, present Calvadosdépartement in Normandy. He married Ealdgyth, the daughter of Wigod, the Saxon lord of Wallingford. After Wigod's death, William appointed Robert the lord of Wallingford, and ordered him to fortify Wallingford Castle between 1067 and 1071. It is believed he may have become the third High Sheriff of Berkshire around this time. He was made Baron Hocknorton. D'Oyly was a sworn brother-in-arms of Roger d'Ivry. 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. His brother Nigel's son was Robert Doyley, the founder of Osney Priory, Oxford. He was also an ancestor of Henry D'Oyly, one of the major feudal barons of the Magna Carta. "He was so powerful a man in his time, that no one durst oppose him", says one account. At Abingdon he was remembered as "a despoiler of churches and the poor until his miraculous conversion ". 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.
Legacy
Robert was appointed High Sheriff of Oxfordshire and ordered the construction of many parts of Oxford, some of which still survive today. Oxford Castle was built under Robert's orders in 1071, and the collegiate church of St George's within the castle was founded by Robert in 1074. The church of St Peter-in-the-East was first mentioned in 1086 as a possession of Robert's although it is possible that he merely acquired it, along with St Mary Magdalen's Church, north of the former gate of Oxford's medieval wall. The monks of Abingdon credited him with the construction of a series of stone bridges at Grandpont, which form a causeway over the River Thames. 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. It is possible however that he merely fortified an older crossing point. Eights Reach, which now forms part of Shire Lake Stream in Christ Church Meadow is also attributed to Robert D'Oyly.
Possessions
Robert owned land in Oakley, Buckinghamshire. The village was valued at £6, and its land consisted of 5¾ hides. With Oakley's clay soil the total cultivated land would have been around. Robert, also, held a tenure in Buckingham held by a man of Azor, the son of Tote, who paid sixteen pence annually and to the King, five pence. The Manor of Iver became part of the possessions of Robert D'Oyly, who held Eureham, for seventeen hides. The land was enough for thirty ploughs. It was estimated at £22, it had been exchanged for Padbury, with Robert Clarenbold of the Marsh. D'Oyly's daughter Maud married Miles Crispin, to whom the Manor of Iver descended. D'Oyly also owned a considerable amount of land in Oxfordshire and in Oxford itself recorded in the Domesday Book of 1086:
Oxford Castle, and the collegiate church of St George's within the castle, that was later acquired by Osney Abbey.
The Castle Mill in Oxford. This belonged to Ælfgar of Mercia before the Conquest and was escheated to the Crown in 1163 following the death of Henry D'Oyly.
The church of St Peter-in-the-East in Oxford, that now forms part of St Edmund Hall.
Land and dwellings in a further 22 Oxfordshire villages.
Family
With his wife Ealdgyth he had a daughter and heiress Maud who first married Miles Crispin, Lord of Wallingford, and afterwards Brien FitzCount, lord of Burgavennu, but leaving no issue, was succeeded by Nigel D'Oyly, her uncle, who was constable to William Rufus and Baron of Hocknorton. Robert and Ealdgyth were buried in the Abbey in Abingdon.