From a number of Trees posted on Ancestry, Mary Ann Bartholomew was born in Hampton, Middlesex in 1866 and was the daughter of John Chapman Bartholomew (c1842 Gouhurst, Kent) and Anne Elizabeth Harvey (c1846 Walworth Surrey). This is Mary Ann in the 1881 census living at 2 Clarkes Cottages,Teddington with siblings & parents:
John Bartholomew 39
Ann E. Bartholomew 35
Mary Ann Bartholomew 15
Alice M. Bartholomew 11
Mabel P. Bartholomew
Her mother's death is noted in 1888. The family do not appear to be listed in the 1891 Census, but her father, who remarried is included in the 1901 & 1911 Census.
Mary Ann's spouse is noted to be Harry Wootten Barnett with there marriage on 12 April 1892, Pietermaritzburg, KwaZulu-Natal, South Africa
"St Peter's Cathedral. He was Hotel keeper in Charlestown and she lived in Pietermaritzburg. Bachelor and Spinster, both of full age. Witnesses E and A Browning. Married after Banns."
Harry's birth in these trees is given as c1864,(not the 1890 you suggest), but with no birth place. Unfortunately there is no categoric reference to a Harry Wootten Barnett in Births between 1855 & 1870. I believe Harry's birth to have been registered as Harry Barnett on the Isle of Wight, Vol.2b, Page 497 q June 1863; as a christening of Harry Barnett on 24 May 1863, WOOTTEN Isle of Wight, the son of Isaac Barnett & Emma is noted. ( https://familysearch.org/ark:/61903/1:1:JQVF-Z78)