Hello Erna and a very warm welcome to RootsChat
I don't know how familiar you are with other online resources but did you see this marriage on the IGI at familysearch.org? It looks promising given the unusual names. It is an extracted entry which means it is reasonably reliable but you would want to check the original parish record to be sure it is accurate, if you think this is your couple....
Simeon Willey m. Sophia Walker
20 Jul 1822
Christ Church Greyfriars Newgate, London
Although the 1841 Census indicates a birth year of 1801 for Simeon and Sophia, enumerators were instructed to round down the birth years for that census so they could actually have been born anywhere from 1797 to 1801.
Sophia indicates she was born in Cheshunt, Herts in the 1851 and 1861 Censuses and the IGI has a baptism for a Sophia Walker (1797 or 8, forgot which year) in Cheshunt, Herts you might want to check out if you think this could be your Sophia.
It is really too bad that Sophia's husband Simeon was deceased by the 1851 Census, with everyone having been put down as born in the county (meaning Kent) on the 1841 Census. If Sophia wasn't born there, there is the possibility that Simeon Sr was born elsewhere also. I couldn't find anything about him on the IGI. Ordering the film of the marriage to your local Family History Center MAY give you a parish other than the one he was married in, which would give you a place to start looking. On the other hand, he could also be from the parish he was married in, so another possibilty there.
I don't know which year your Thomas was born in? If it was before birth registrations began in July 1837, you might consider obtaining the birth certifcate for his brother Simeon who appears to have been born in 1839, judging by the 1851 Census? This should give you the mother's maiden name to check against the marriage above.
Hope this will start you off without overwhelming you.
Regards,
Polarbear
