I now have in hand the 11 August 1847 certificate from her first marriage, to John Emmott:
1847, Marriage solemnized at Register Office, Skipton in the District of Skipton Union in the County of York
Eleventh August 1847 Skipton
John Emmott, full age, Bachelor, Weaver, Cowling, father John Emmott, Weaver
Nancy Harker, full age, Spinster, Weaver, Cowling, father James Harker, Weaver
Married in the Supt Registrar's Office before
Charles Carr
Supv Registrar
Benson Bailey
Registrar
John Emmott signs
Nancy Harker makes her mark
Witnesses
Jesse Fairbank
Mary Crossley Fairbank
I have more than one reason to believe this is the right person. Father's name and occupation match those on her marriage to Robert Pickles. Both ceremonies are non-con. She is a weaver on both (and also on the 1851 census I think is her, so another point in favor of that census appearance too). She also makes her mark at both marriages. So, unless somebody contradicts me, I think this is right.