Sydney Smith

Sydney was the husband of Verity and the father of John Smith. They raised John on Broadmarsh Street in Radford Parade in the district of Nottingham. (TV: Human Nature) After he and his wife died the family maid, Martha Jones, continued to serve John. (TV: The Family of Blood)

Behind the scenes
John's parent's names Verity and Sydney were a tribute and reference to Verity Lambert and Sydney Newman, both essential to the making of Doctor Who.