 Tennant was unsuccessful when he tried to contest Peterborough that year.In 1850 he married Harriete Garnett (d.1899), a daughter of the newspaper proprietor Jeremiah Garnett (1793–1870), of Mount Broughton, Manchester, by whom he had 7 sons and 4 daughters, to all of whom a mural monument (post 1936) survives in St Mary's Church, Conistone, as follows