The British military no longer pours its resources into this low tidal island in the River Medway, but you could, with the freehold on this 19th-century sea fort, originally designed to hold 100 men. Listed with a guide price of £50,000 via Savills, Darnet Fort once formed part of an inner defensive line protecting the approaches to Chatham’s naval dockyard. Together with its companion fort on Hoo Island, 1km upstream, it formed a strategic ‘bottleneck’ of perfect circular ramparts.
The fort was designed for two tiers of guns, though spiralling costs meant the planned boom between the paired structures was never realised. Built between 1870 and 1872, Darnet was decommissioned before the First World War. The site later served as a Second World War observation post, with pillboxes and platforms added to its roof.
Today it remains vacant, its magazine level flooded and its masonry still carrying the geometry of 19th-century naval architecture. Listed as a scheduled monument and accessible only by private boat, it includes three sunken barges and part of the estuary within its freehold.

Photography courtesy Savills.

Photography courtesy Savills.

Photography courtesy Savills.
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