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I located the 1824 Tithe record for the McCarthys and Kents (see below). They had fairly large holdings. The townland was Ballyhamsherry. I checked the 1852 Griffiths Valuation head of household listing for Castlelyons civil parish and although there were McCarthys and Kents in the parish, they were not shown in Ballyhamsherry. Regarding John McCarthy, I can only assume he died. There are no death records in the parish register http://registers.nli.ie/parishes/0028 and civil registration did not start until 1864.