This Isabella was nee Hardy and married John Dent in Lanchester March 1/4 1893 vol 10a page 349. He born Hunstanworth c1868.
I can't find a death of a John Dent 1911 - 1913 of suitable age which would allow this Isabella Dent to marry John T Walker.
Wow. Feels like one step forward one step back.

I've spent all day today on one of my own Dents, i.e. James Dent son of George and Isabella. I was really thrown off the scent by wrong transcription shown in a number of census records. For example James married a Mary and in 1881 there is John Treworth who was born in the same Yorkshire village as Mary. Turns out her name was Toward and the village varies from Lanesend to Langsdale to Langisdl to Lunedale in various census. Lunedale is correct and it was way up in Teesdale, once Yorkshire now Durham.
Lanchester was the registration district for Consett and Blackhill, so I suspect that John and Isabella Dent nee Hardy moved from Hunstanworth to Consett as did so many others from the defunct Lead Mines of Hunstanworth.
How sure are we of John's birth year as 1868? Just a thought that he may have been a bit older and so one of the other many John Dent's in the 1911 census. I think Ann in New Zealand is going ahead and ordering the marriage cert for Isabella and John T Walker which of course should solve this mystery.
Again thanks for all of your help. Malcolm