In the 1841 census and the 1851 census, there is an Ann Watt listed on the same entry as David. Her age was given as 20 and 28 respectively. She does not appear in 1861.
However she may have married William Watterson June 22 1858 , as Anne 40, William 40, James 2 and Arthur (1 month) Watterson are in the 1861 census at the same address with two other sons Henry 13 and William 10, from before the marriage: Henry Watt chr. Jan 2, 1848. William Watt Chr. June 15, 1851.Henry appears as Henry Watterson in the1851 census.