Margaret nee Cain and John Kewley don't seem to be on the IOM in 1861. On the mainland, there's a 31 yr old married Margaret Kewley at 116 Windmill St, Gravesend, Kent, wet nurse, B IOM. She's in the household of Charles Edward Parker Gordon, a Lieutenant in Army 75th Regiment. If this is your Mgt Kewley alias Thompson nee Cain, could it be that John Kewley was a soldier and that while he was away, Margaret provided the services of a wet nurse, perhaps having given birth to a baby who had died ? Just a theory.

Jean