As they could not read or write is it possible a mistake was made on the marriage certificate.
What address did he give on the certificate because Luke and Harriett Kerley/Kerly always lived on Southampton Street.
1891 census Joseph is a widower 44 his age is off s/b 49-51 with 2 daughters Alice 20 and Ruth 18 still living with him they are lodging with a Mary Clack age 41 on Southampton Street. Then go back to 1851 on Southampton Street 3 doors up is the Clack family Mary being the youngest.
Just in case using the new GRO Index, the last 4 children of Luke and Harriett nee Bellinger, Mark, Elias, Arthur and Luke were all registered as Kerly, mmn Bellinger except Mark when it is spelled Ballinger.