Apparently, she was engaged or had planned to marry a local 'labourer' - William Webb, supposedly of an extensive land-owning family of Essendon, Hertfordshire - but he was killed in a 'tragic accident' of some kind, in August of 1833. Mary Ann King was already pregnant and gave birth to their son, William (Webb-King) in Essendon, on 5th of January, 1834.
Mary Ann King married William Frost (c. 30 May, 1819) of Much Hadham, Herts in 1848, at Essendon. She took in work as a laundress, with her mother Sarah (Lawman) King. In the 1851 Census, she was living at 'Laundry Cottage,' Essendon. Their children were born in Essendon: William Henry, Frederick, Mary Anne, and Charles.