Reginald was born in Dénestanville in the Duchy of Normandy, an illegitimate son of King Henry I (1100-1135) by his mistress Sybilla Corbet, a daughter and co-heiress of Sir Robert Corbet lord of the manor of Alcester, Warwickshire, who was at some time the wife of "Herbert the King"s Chamberlain". Reginald"s sister was Rohesia, wife of Henry de Pomeroy (died c1135), feudal baron of Berry Pomeroy in Devon.
He became Earl of Cornwall and High Sheriff of Devon. The title Baron de Dunstanville was created in 1797 for Francis Basset of Tehidy in Cornwall. In about 1173 he granted a charter to his free burgesses of Truro in Cornwall, and addressed his meetings at Truro to "All men both Cornish and English" suggesting a differentiation of nations.
He served as High Sheriff of Devon from 1173-1174.
Illegitimate progeny He died at Chertsey, Surrey, and was buried in Reading Abbey.
