Have you checked birth reg for all of Thomas and Emily's children - and what their names on marriage were??
Suz
Here is what I have found on freeBMD:
1871 census - surnames Maidmont:
Mary Jane MAYNARD on BMD Sep 1868 6a 149
Louisa Maidmont no trace on BMD and not on any further census
1881 census - surnames Maidment:Minnie b. 1870, no trace on BMD
Thomas - Thomas Henry MAYNARD on BMD Dec 1872 6a 153
Heald b. 1878- no trace on BMD
James b. 1880 - could be BMD: James Alfred MAYNARD b Dec 1879 6a 202
1891 census - surnames MaidmentSelina b.1878 - on BMD as Selina Maria MAYNARD b Dec 1877 6a 196, also marriage to William Charles King 18 Sep 1898 6a 250 (MAYNARD)
Gilbert b. 1883 on BMD as Gilbert MAIDMENT b Mar 1883 6a 189
Frederick b 1887 - on BMD as Frederick John MAYNARD b Sep 1886 6a 185
1901 census - surname MaynardEthel b 1890 - on BMD as Ethel Minnie MAIDMENT b Jun 1890 6a 183 Added to say - father is listed as Thomas and mother as Selina!! - possibly Selina went to help register the birth rather than Emily??
What was very intriguing is that I can't find any of Henry and Sarah Maidment's children on BMD under either Maidment or Maynard exc a few possibilities for Thomas, but I did find Sarah Ann, Thomas and Martha's christenings on Family Search under Maidment.