tricia, found this birth and wonder if this is your mary ann, the only thing is she would have being age 30 when she married,see what you think. i guess she was from derry/londonderry not as you thought tyrone. normally the marriage took place in the girls parish.
birth.MARY ANN DOWNING B.23-2-1871. BELLAGHY, MAGHERAFELT, BALLYSCULLION, CO. DERRY.
parents. WILLIAM DOWNING & ROSE MULHOLLAND.
p.s are you sure of james birthplace.
regards mary.