Robert Frew Snr and wife Mary Bre/ackenridge married on 11 December 1863 in Glasgow/Blythswood.
I think this is them in 1881:
Robert Frew 40 blacksmith b. Stevenson Ayrshire
Mary Frew 38 b. Ireland
Robert Frew 15 warehouse boy b. Glasgow
William Frew 2 months*
Mary King 16 Servant
Address 288 Cumberland St, Glasgow/ Hutchesontown
* William's birth entry registered as William Breckenridge Frew, b. 2 Feb 1881 in Glasgow/ Hutchesontown.
There is another couple in Ayrshire, Robert Frew and Mary Scott, having children at the same time and muddying the waters

Monica