Hello Sue, I found this information on the internet giving the baptism date for John Corkill and his brother Thomas Corkill.

Manxman John CORKIL (KALKHILL) b. 14 mar 1773 Malew arriving some time end of 1700's.

The John who arrived from IOM had a brother Thomas b 8 Nov 1771.

John Cockle married Anne PHILIPS Madron 14 Jan 1802. They had a number of children possibly 8 or 9. He seems to be recorded as COCKLE in Madron/Penzance Baptism registers. I can find,
3 John COCKLE's (bpt Aug 1802 and in 1804 and Jan 1805)
George Phillips COCKLE (bpt 5 May 1809 Penzance)
Jane Phillips COCKLE (Married James Opie Jun 1834)
William and Mary COCKLE (twins) bapt 24 Sep 1806,
Anne COCKLE (b 25 sep 1816),
Priscilla CORKELL 26-May 1819
Isabella COCKLE b circa 1822. She married John BUCK Mardon Sep 1851.

also:
Ann Corkell buried 1848 Age 73

William Corkill buried 1862 age 55 residence Quay
Elizabeth Cockle buried 1865 age 61 (William’s Wife)

and in 1862 a baptism of Jane Janette Corkell to Priscilla of Union Workhouse

hope this helps,

Averil