More info from the newspaper reports - Sir William is said not to have been an MP but to have been an unsuccessful candidate for the East Kent constituency.
He was born in Devonport, son of a baker. He entered the Navy and worked his way up to the position of secretary to Lord Collingwood, who thought so highly of him that he offered him his daughter's hand in marriage. The daughter was not unwilling, but before a marriage could take place the unfortunate William was seriously injured in a horse and gig accident near Temple Bar in which both his legs were broken when the shafts of a cart penetrated them. The young lady waited three years for him to recover (physically and mentally) but eventually gave up on him and married someone else. When he did recover he married the daughter of Mr Halliday, a partner in the banking house of Harries, Farquhar & Co.
Summarised from an entry in the Kentish Gazette, 17 June 1834.