Fort Cumberland is an 18th century fort built on the shingle spit of Eastney Point on the south eastern corner of Portsea Island. It is a Scheduled Ancient Monument (Hampshire monument no. 277) and is the home of English Heritage's Centre for Archaeology. It is described in the English Heritage's Visitors' Handbook as 'perhaps the most impressive piece of 18th century defensive architecture in England'. A watching brief was undertaken during the replacement of the underground power supply cable from the security office to the coastguard offices in the Ravelin via the Parade Ground and Land Curtain. Nothing of significance was recorded during this work.
Gillian Owen (2025) studied this question.