FreeBMD according to their coverage charts has complete coverage of GRO marriages for the year 1838. No Beaumont marriages at all in Norfolk and for Beaumont marriages across the country no Emilys or Sophias. No Emily Sophia or Sophia Emily 'any surname' for 1838 either. Nothing for the surname Beaumont on the IGI either for Norfolk for 1838 but Bramerton has no coverage on the IGI (where the Beaumont family was living on the 1841 census). Bramerton is in Henstead registration district. Approximately 110 marriages are recorded in Henstead registration district for 1838 on FreeBMD - nothing looks remotely likely.
You can see FreeBMD coverage charts for marriages for yourself at
http://freebmd.rootsweb.com/progressM.shtmlalmost complete coverage July 1837- 1843.
The eldest known child for the couple was Henry 'Bernard' with a birth year of circa 1844 (from the 1851 and 1861 censues).
The other children's births were all registered.
Births Dec 1846
Green Harriet Augusta Eastbourne 7 347
If you killed someone fairly prominent in a duel, which was treated under the law as a capital offence, I'm not sure laying low in France for a couple of years and then returning under an assumed name, but being relatively easy to find, would necessarily stop the inevitable process of the law?
Regards
Valda