Interesting find.
Jacob Coulthard was living a few doors down from Martha and her Father George Cowie in 1891.
He was aged 7 so did Martha age 20 used to babysit him  

George Cowie and Jacob's father both worked at Consett Steel Works.
1891 Census 
Residence Place:
Consett, Conside and Knitsley, Durham, England 
Registration district:
Lanchester 
Sub registration district:
Consett 
ED, Institution or Vessel:
7 
Piece:4090 
Folio:42 
So yet more proof to connect Martha and Jacob