Have you looked for Ann's birth or christening in Canada? A lot of Orkney men spent some time in Canada at Hudson Bay Company. I assume that her father may have been a sailor if she was in Durham when she was married. Also I would be looking for her christening after 1830, children were not always christened at the time of birth, I have some who were christened as old as 11. Where did you find her in the 1841 Census and where did you find her in the 1861 Census? Where was Ann when she died, her death certificate may have both parents name on it as long as it was not England.