OK, velcro, I think I have it sorted for you
The Mary Jane Barker, dtr of John and Ann, that you are refferring to, is the one born 1843 ish, daughter of the John who is on your original list, and therefore grandaughter of the original John and Ann (nee Elmes).
She is the one I found with them in the 1871 census at North Lane Farm in West tarring, at that time she was 28, single and described as a "land owner".
By 1881, John and Ann her parents had died (I found the deaths for you) and it must be this John's will you have (he was born 1812 and died end of 1880 - dies that fit in with the date will was written and proved?).
Mary Jane must have just married H H Gardner - the 1880 date you have is correct:
Jul/Aug/Sep 1880 East preston 2b 583, Mary Jane Barker to Henry Humphrey Gardner.
ANd here she is in 1881:
RG11 1118 32 11
Church Farm West Taring
Henry H Gardner 40 Farmer
MAry J wife 38 bn West Tarring
Ellen 17 visitor
plus 2 servants.
Now, you could have found this entry yourself, 1881 is free to view, and the marriage is on freeBMD, and worked it out yourself! I have given you all the cesnsues for every child of John(senior) and Ann that arent on a free to view site.
One tip - watch dates carefully - there is no way this Mary Jane could ever have been the one on your original list, bn 1811ish.
Which leads us to beleive that the one who married Geroge Golds IS that one.