Hi there!
Been having a look for the marriage, but no luck so far.
In the meantime, I suspect you don't have the full transcription because Edward was neither the youngest nor the eldest. Additionally, I'm fairly sure that Michael was 40 - not 60!
1841 Census of St Mary Dover
HO107/949/9 folio 16 page 23(?)
"Commercial Quay"
Michael Ellen, 40, mariner
Charlotte do., 30
William do.,12,
Edward do., 9
Adelaide do., 6
Stephen do., 4
Alfred do., 2
Sarah Dennis, 11
William Dennis, 11 (or 14?)
If we assume that William was their eldest son, it might be useful to find his baptism record or find him in a later Census. With his place of birth, there's a better chance of locating his parent's marriage.
Cheers
Dave