I have an address of 6 Oxford St. Stockton-on Tees for George Smith which is probably right as my father came from Middlesborough.
Yes, that is where they were living in the 1881 census.
Either one of Ruth's marriage certificates ought to give her father's name.
Marriages Mar 1867
ERSKINE John Henry Cockermouth 10b 645
LAWSON Ruth Cockermouth 10b 645
Marriages Dec 1873
ERSKINE Ruth Stockton 10a 211
SMITH George Stockton 10a 211