Hi
You haven't given any details of when their first child was born which gives a clue to a marriage date. His marriage cert should have his fathers name
Shared Facts: Ann Fern
Has her maiden name been confirmed from one of their children's birth certs
This is the full 1851 entry which suggests the marriage was in the 1840's
John Ryan 34 b Newport
Ann 35 b Shropshire
Thomas 2 b Lantripent, Glamorgan,
Ann 6 b Langmenver, Glamorgan
Catherine 5 ditto
HO107 Piece 2452 Folio 140 Page 34