Is this who you are looking at as potentially the family for James Snr.? From 1891:
Peter McWilliam 41, Traction Engine Driver, Forfarshire, Craig
Elizabeth McWilliam 41 b. Forfarshire, Brechin
Jessie H McWilliam 13
James G McWilliam 12 b. Elginshire, Drainie
Maggie McWilliam 7
Hugh Wilson 23 boarder
Address: 1 St Mary St, Peterhead, Aberdeenshire