The Illsley and Ilsley names derive from a pair of hamlets in Berkshire - East Ilsley and West Ilsley, which are mentioned in the Domesday Book (1888)as Ildeslei and this refers to a clearing (lea) belonging to Hild. So Hild's lea. The earliest record of a person using the name is Isabella de Idleslei in 1297. Some early versions of the name were spelled with Ie and D: e.g. Ieldsley, Ildesly.