Maybe this is the Angus Cowle mentioned in your letter
Angus Munn Cowle ch 11 AUG 1822 Ballaugh, Isle Of Man
Father Thomas Cowle
Mother Leonora Clarke
md
25 OCT 1814 Ballaugh, Isle Of Man

He is a contemporary of the children of James Craine and Isabella Kneale of Ballaugh.

Angus seems to be a family name. There is a young Angus in 1851 Ballaugh census who is nephew of the above Angus (child of his brother Charles)
Ballaugh, 01-01, 004, COWLE, Charles, Intack, Head, Married, 34, Farmer 12 Ac, Ballaugh
, , , , , , , , , Prop 4 Ac
, Ballaugh, 01-01, 004, COWLE, Margaret, Intack, Wife, Married, 36, , Malew
, Ballaugh, 01-01, 004, COWLE, Thomas, Intack, Son, , 3, , Ballaugh
, Ballaugh, 01-01, 004, COWLE, Angus, Intack, Son, , 1, , Ballaugh
, Ballaugh, 01-01, 004, COWLE, Edward, Intack, Son, , 5mo, , Ballaugh
, Ballaugh, 01-01, 004, COWLE, Leonora, Intack, Mother, Widow, 67, Annuitant, Jurby
, Ballaugh, 01-01, 004, KNEEN, John, Intack, Servant, , 15, Gen Servant, Ballaugh