I wondered whether John was with him because both Robert and John were missing from the IOM 1871 census.

(Census from Brian Lawson)
1861, Maughold, 4425/11/76, Dreemskerry
Robert Corkill, head, married, 41, blacksmith, Maughold
Catherine, wife, married, 42, Bride
Esther, daughter, unmarried, 19, servant maid, Maughold
Robert, son, unmarried, 17, blacksmith, Maughold
Catherine, daughter, unmarried, 16, Maughold
John, son, unmarried, 12, scholar, Maughold
Ann, daughter, unmarried, 9, Maughold
Eleanor, daughter, unmarried, 7, Maughold
Edward, son, unmarried, 4, Maughold
Isabella Margaret, daughter, unmarried, 1, Maughold.

Sue