Hi - It looks as though Eric is right.

This is a Household transcription from Findmypast for the 1851 census:

Name Relation Condition Se x Age BirthYear Occupation Where Born
CORKILL, William Head Married M 44 1807 Farming 48 Acres & Employing 1 Lab Onchan
CORKILL, Margaret Wife Married F 41 1810 Onchan
CORKILL, Margaret Daughter Unmarried F 17 1834 Onchan
CORKILL, William Son Unmarried M 16 1835 Farmer's Son Onchan
CORKILL, Isabella Daughter Unmarried F 14 1837 Onchan
CORKILL, Robert Son M 12 1839 Onchan
CORKILL, Mary Ann Daughter F 10 1841 Onchan
CORKILL, Joseph Son M 8 1843 Onchan
CORKILL, Elizabeth Daughter F 6 1845 Onchan
CORKILL, Georg Henry Son M 3 1848 Braddan
CORKILL, Eleanor Jane Daughter F 1 1850 Braddan
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Piece:2525 Folio:468 Page:18
Civil Parish:Braddan Municipal Borough:
Address:
Balla Kewish, Braddan County

The IGI has an earlier William James and an earlier Eleanor - presumably both died before their namesakes were baptised, and a later child Joseph Quirk Corkill b.1851, so that makes 12 children that I have seen.

Sue