Bull Sandfort, a Grade II listed sea fort located in the Humber Estuary went up for sale at Savills most recent auction.

It follows the sale of its smaller sister fort, Haile Sand Fort, which sold for £117,000 at auction in 2018 to an unnamed purchaser.

The fort was planned in 1914 at the start of the First World War to protect the sea entrance to the Humber Estuary. Construction began in 1915 and was not complete until December 1919. It was then reactivated and modernised during the Second World War.

Structurally, the fort includes three floors with basement and magazine below sea level, and a central two-storey observation tower. It is reinforced by concrete and its seaward side is fitted out with 12 inches of armour designed to withstand gunfire from heavy naval units. During World War II it had sufficient accommodation for a garrison of 200 men. The fort can only be accessed by private boat and helicopter.

Steven Morish of Savills said: “This is an exciting and unique lot, the fort is in need of refurbishment throughout with potential for development or alternative uses subject to consent. It will require an imaginative buyer with a project in mind but suggestions for future uses so far have included a high-end hotel, restaurant, Airbnb, grand design style personal dwelling, retreat and a tourist attraction.”