You know I'd looked at 1851 census and mustn't have clicked with John senior.
I'm just 'talking out loud' now to go over what you have re the older Reddingtons.
1843 Luke Doyle m Catherine Griar (nothing to do with your case I know)
1847 Luke Doyle dies.
1850 (Jun quarter) John R marries Catherine Doyle
John must have been in England from at least beginning of 1850.1851 census - Brown Street - John snr and John
the two Reddington children on that census are in fact Doyles.
1851 (December quarter) Bridget Reddington m Patrick Callaghan
do the witnesses at this marriage give any credence to these connections?
Erin I know you have researched them all especially your 3 x gt grandparents
so sorry if you have this already:
1851 Brown Street ( a couple of entries further on than the Reddingtons)
Patrick and Elizabeth Gahagen with a sister Bridget 21 yrs and a sister in law Mary 23 yrs. Both these are unmarried and listed under Gahagen but can't really both have the same surname.
Further on again, there is a Mary Calhagen with children including son Patrick 21 yrs, daughter Betty 23 yrs. (I think I saw a Betty living with Patrick and Bridget later).
well that's it again

best wishes
heywood