Mercy was indeed born 1847 & baptised 16 May 1847, Bromley Kent. She was the daughter of Henry Bennett. (http://Ancestry.com. England, Select Births and Christenings, 1538-1975).
She married Henry William Kadwell, 4 September 1864, Bromley, Kent ( http://Ancestry.com. England, Select Marriages, 1538–1973: FHL Film Number: 1042455 )
Her death is recorded in 1868, Bromley Mercy Cadwell. See earlier answer.