William's first marriage was to Mary Cornfield on 28 February 1797 at Wellingborough, Northamptonshire, and they had 6 children: - Ann Simpson born 1798 and died 1885 - George Simpson born 1800 and died 1888 - Elizabeth Simpson born 1802 - John Simpson born 1804 and died 1867 - Frances Simpson born 1806 - Thomas Simpson born 1809 and died 1880
Mary presumably died sometime between 1809 and 1812.
William then married Ann Eaton in 1812 at Pytchley, and had 6 children: - Jane Simpson born 1812 - Eliza Simpson born 1813 - Susannah Simpson born 1815 - William Simpson born 1817 - Lydia Simpson born 1820 and died 1830 - Samuel Simpson born 1823 and died 1895