Looking at 1851 census she is a widow, with a niece and nephew living with her. Niece is Mary Jane aged 15, and nephew is John Ley Nosworthy aged 7, looking on GRO site for births, it gives his mothers maiden name as Osman. So PERHAPS Susanna was an Osman? and young John has been named after his Godfather/uncle.(could be great nephew and niece but worth investigating further).
He was born Exeter, sister born Highweek, where there is another connection, a Charlotte Caunter daughter of George Caunter married 2.7.1831 a John Ley, his father named John. Another line worth investigating. It sometimes pays to go sideways and establish links that way.