I'm really stuck with my O'Neil/O'Neill family in Widnes

.
I have them on 1881 at 54 Cromwell St and 1891 at Reil St. In 1901 I can find some of the children but not the parents.
I'm looking for Thomas and Mary O'Neil/O'Neill who would be app 56 & 53yo in 1901. I don't know their place of birth other than Ireland. I've tried to find a marriage between then prior to 1870 but haven't been successful. Mary's maiden name was Ward. Of course, they could have been married before coming to England.
In 1901 census I can find 4 of their children (1 Mary is married to Joseph Newall and has 3 of her younger siblings with her, names are Annie, Daniel and Ellen). 2 siblings (Christopher & Thomas) are in Swansea.
I've tried ancestry.co.uk and also the search engines on The Geanealogist but am coming unstuck all of the time.
All suggestions would be very welcome.
Deb
PS have posted this on cheshire board too.