Hi Sheena
A search of marriages on Scotlands People indicates Patrick and Mary are likely to have married in Falkirk in 1889. This looks like them in 1891:
Patrick Robertson 26, moulder, b. Laurieston, Stirlingshire
Mary McCall 24, wife, b. Laurieston, Stirlingshire
Catherine Robertson 2, b Laurieston, Stirlingshire
Address:South St, Falkirk Landward
Monica