Here are the three baptisms of the Manx-born children (no father's name on any of them):

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Mary Ann
Isle of Man Parish Registers
Event Type Christening
Event Date 15 Jul 1830
Event Place Andreas, Isle of Man
Gender Female
Mother's Name Ellinor Corlett

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Name Ellinor Corlett
Gender Female
Christening Date 11 May 1831
Christening Date (Original) 11 MAY 1831
Christening Place ANDREAS,ISLE OF MAN,ENGLAND
Mother's Name Ellinor Corlett

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John William
Isle of Man Parish Registers
Event Type Christening
Event Date 27 Oct 1833
Event Place Andreas, Isle of Man
Gender Male
Mother's Name Eleanor Corlett

Image shows “base born son of Eleanor Corlett”

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Perhaps John Brew married Eleanor Corlett in the period between leaving the IOM in the mid 1830s and the start of civil registration in England in 1837 ---- so no record available online ?

Or maybe they never actually married ?

Jean C