In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Alciston like this:
ALCISTON, a parish and a hundred in Sussex. The parish lies in the district of Lewes, 1 mile S of Berwick r. station, and 6½ SE of Lewes. Post Town, Selmeston under Lewes. Acres, 2,079. Real property, £1,596. Pop., 220. Houses, 47. The manor belonged anciently to the Abbot of Battle. ...
The surface is hilly. The living is a vicarage, united to Selmeston, in the diocese of Chichester. The church shows features of Norman and of early English, and is in tolerable condition.-The hundred of Alciston is in the rape of Pevensey, and comprises the parishes of Alciston, Alfriston, and Lullington. Acres, 5,666. Pop. in 1851, 859. Houses, 181.
GB Historical GIS / University of Portsmouth, History of Alciston, in Wealden and Sussex | Map and description, A Vision of Britain through Time.
Date accessed: 27th March 2017
Click here for more detailed advice on finding places within A Vision of Britain through Time , and maybe some references to other places called " Alciston ".