Gillie,
The Newcastle Courant, 1 Jan 1820, reported the marriage -
"Thursday se'nnight, Mr Wm Weatherstone, slater, to Miss Christian Sutherland, daughter of Mr Alexander Sutherland, Innkeeper, all of Berwick". But I can't find a Parish record of the event.
In the absence of marriage details and ".... no children ....", what is the source of Isabella's surname before marriage "Thompson"? I've checked the Census 1841-1881 and no clue there. What I did find unusual was the consitency of Isabella's calculated year of birth - always 1804 ( including even 1841!)
Familysearch has an Isabella Thompkins, born 31/1/1804 and christened 18/2/1805, Chapel Street or Shaws Lane or Relief Chap, United Berwi, Berwick upon Tweed (batch no C080401). That's the closest I can find on line