Hi,
I noticed in the 1911 census that William John and Susan had been married for less than 1 year and were described as Presbyterian. The census was conducted on 2 April 1911 and I have found a marriage of a William John Bailie and Susanna Montgomery in Comber 2nd Presbyterian Church, Newtownards on 27 April 1910. Don't know if this is revelant.
Regards