Faversham and Lydden are both about 15 miles from Blean in opposite directions. So the chosen records for Mary Ann are based in the 1871 census being correct in giving her birth date as 1845.
Sources
↑ "England and Wales Marriage Registration Index, 1837-2005," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:2D7Q-GXR : 13 December 2014), George Spicer, 1864; from “England & Wales Marriages, 1837-2005,” database, findmypast (http://www.findmypast.com : 2012); citing 1864, quarter 3, vol. 2A, p. 980, Blean, Kent, England, General Register Office, Southport, England.
↑ "England and Wales Census, 1871", Murton Cottages, St Mary Bredin, Canterbury, database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:VF8G-TQ3 : 12 December 2017), M A Spicer in entry for George Spicer, 1871.
↑ "New Zealand, Archives New Zealand, Passenger Lists, 1839-1973," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:FS1Z-D3K : 10 August 2017), Mary A Spicer, 1875; citing ship Hannibal, Archives New Zealand, Wellington; FHL microfilm 4,412,551.