Yes, this fits with the newspaper record that says she was 15 in 1879, putting her birth around 1863/4.
freebmd.rootsweb.com shows a marriage in 1860 in Monmouth district for Henry Watkins and Sarah Price.
That would fit with this family in 1871 (think some of the place names are off)
RG10-2599 40/29
Dog Inn, East Dean, Gloucestershire:
Henry Watkins, 35, married, collier, b. Monmouth St. Briavells
Sarah, 30, wife. b. Gloster Pillowell
Mary Ann, 9, dau, b. Gloster Whitecroft
Eliza, 6, dau, b. Gloster Respage (Ruspidge?)
Charles, 3, son, b. dit
Henry, 1, son, b. dit
Another daughter, Alice Watkins, aged 10, b. West Dean, is in the 1871 census with her Price grandparents:
George Price, 64, coal miner, b. West Dean
Eliza, wife, 53, b. Coleford Glos.
Charles, son, 14, coal miner, b. West Dean
Alice Watkins, grand-daughter, 10, b. West Dean
(+ lodgers)
By 1881, Alice is back with her parents, with the addition of a few younger siblings.
Mary Ann (9) and Eliza (6) from the 1871 census
https://familysearch.org/pal:/MM9.1.1/X3BC-S6KEliza I think is possibly the 15 year old aboard the Hydaspes in 1878, arriving to NZ, listed as a domestic servant from Gloucestershire:
https://familysearch.org/pal:/MM9.1.1/FSBK-5MXThere are some old messages out on the web about this family. This says Mary Ann married Moses Everett (and this marriage appears in 1878 in NZ)
http://www.forest-of-dean.net/fodmembers/index.php?mode=thread&id=15867If this is right, then Martha had an aunt and a number of cousins also in NZ. Mary Ann's husband Moses died in 1913 in a work accident which puts them in Addington at the time.