I can find no record for either George Isles nor his brother Joseph.  There is, however a entry in the 1901 census ...

North Side, North Street, Cargill, Perthshire

David Isles, head, 37, railway surfaceman, b. Cargill

Mary Ann Isles, wife, 37, b. Errol, Perthshire

Andrew Isles, son, 11, scholar, b. Cargill

Margaret Isles, daughter, 10, scholar, b. Cargill

Joseph Isles, son, 8, scholar, b. Cargill

Charles isles, son, 6, scholar, b. Cargill

James Isles, son, 3, b. Cargill

George Isles, son, 1, b. Coupar Angus, Perthshire

There is an entry on the CWGC site for a J Isles of the 11th Bn., Border Regiment.  He is down as the son of Mr. & Mrs. David Isles of Scott Street, Burrleton, Perthshire.  This is not very far from Cargill.