A Vision of Britain through Time provides the following description of Blackmanstone from John Marius Wilson's Imperial Gazetteer of England and Wales of 1870-72:
The parish was abolished in 1934 and the area split between the parishes of Newchurch, Burmarsh and St. Mary in the Marsh with the largest portion going to Newchurch. The area is now all within the Shepway District of Kent.
There is no description in Wikipedia.
Kent Research Tips
This list has been taken from GENUKI where more places and websites for researching are listed.
Archives and Libraries
Civil Registration and Census
Family History Societies
Most of the county is divided between the Kent FHS and the North West Kent FHS.
Kent Probate Records Numerous links provided by Maureen Rawson