I agree with Jim1 that he would have been too old for service in WW1.
Having said that, there maybe a connection to your family. The Samuel Lavery that you were asking about, married in 1915 and he died on the 23/12/1919. A couple of pension records show that his widow, Sarah Ann, was living at 138 Argyll Street, Belfast - you mentioned that his brother lived at 136 Argyll Street in 1911.