Thanks to MNB CD Rom I found their wedding.
William has married with his father's consent...so how old does that make him?
Recorded as from Bark in K.M. but I can't find his christening. Thomas Kelly from Baark has several sons, but none named William!!!! Catherine married with her guardian's consent. I believe she is illeg. daughter of Margt Cannell and Patrick Hiennes. This fits with oral family history. If any child threw a temper tantrum in our family it was said that we were displaying the 'Kelly Pat Hinds' blood. So there's some association here that meets past memories / criteria.
I suspect Margaret Cannell then married John Grimshaw in 1750. Catharine christened 1749.
Any help would be appreciated.