According to the 1911 census, Mabel worked as a domestic servant for Mark and Margaret Madill and their family.
No more info is currently available for Mabel Jackson. Can you add to her biography?
"England and Wales Census, 1891," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:7D2L-7T2 : 11 December 2017), Mabel Jackson in household of Beaumont Jackson, Hipperholme With Brighouse, Yorkshire, Yorkshire (West Riding), England; from "1891 England, Scotland and Wales census," database and images, findmypast (http://www.findmypast.com : n.d.); citing PRO RG 12, Yorkshire, Yorkshire (West Riding) county, subdistrict, The National Archives of the UK, Kew, Surrey.
It may be possible to confirm family relationships with Mabel by comparing test results with other carriers of her mitochondrial DNA.
However, there are no known mtDNA test-takers in her direct maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Mabel: