Thanks for the information. Burns looks to be the best bet of those suggested. Getting hold of a marriage certificate will be the next step.
1891 just has Cornwall for birthplace born 1827
1901 transcribed as Burrs has Lancallas Cornwall born 1827, when you look at the image it looks like Lanoellas which is pretty close to what you said with Lanallos.
As for a death there’s a Mary A Burn age 94 death in 1919 East Stonehouse. Closest I can see so far.
Also a John Burn age 92 death in 1919 East Stonehouse. Likely to be that couple I think but we still haven’t proved she was your Mary Jane Brock.
I've yet to investigate Mary Jane's siblings. She was with elder sister Rebecca in 1841 if I have the right record. There may be some clues to be had there.
I don't know if she had any more children with Edward Brock. Married in 1861, he was born in 1862 and then Edward died in 1870. It's unusual in my tree to have a single child but she was almost 40 at that stage.
I will get back on this later this evening. Thanks again.