I was just coming to the same conclusion as amondg
In the 1921 census Jane Jackson (mother) is 52.2 born Shildon.
There is a marriage:
All Saints, Stranton, County Durham
17 Nov 1888 George Jackson (of Belle Vue Terr., age 20, bachelor, blacksmith, son of Thomas Jackson, blacksmith) married Jane Sykes (of Owton Fence House, age 19, spinster, daughter of William Sykes, engine fitter)
Witnesses: Elisha Teasdale Sykes; Ruth Jackson
This family (based on the age of Jane Sykes and the presence of a brother Elisha and father William) is in Shildon in 1871.
This would put the marriage after the birth of Jenny in 1896.
It was early, I wasn’t thinking straight!