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Grimsby Old Blockhouse

Also known as, or recorded in historical documents as;
Tresco Old Blockhouse; Dover Fort

In the civil parish of Tresco.
In the historic county of Isles of Scilly.
Modern Authority of Isles of Scilly.
1974 county of Isles of Scilly.
Medieval County of Isles of Scilly.

OS Map Grid Reference: SV89721546
Latitude 49.95852° Longitude -6.32755°

Grimsby Old Blockhouse has been described as a certain Artillery Fort.

There are masonry ruins/remnants remains.

This site is a scheduled monument protected by law.
This is a Grade 2 listed building protected by law*.


Old Blockhouse, as it is known, was built between 1548 and 1552 as a raised gun platform with adjoining living quarters. In 1652, it was referred to as 'Dover Fort' in a Parliamentary Survey of Scilly. The blockhouse is situated on a low headland at the south east edge of Old Grimsby Harbour, on the east coast of Tresco. It commands a field of fire to the north west, across the harbour and to the north east between Tresco and Tean. The blockhouse forms part of a series of fortifications built on Scilly between 1548 and 1554 in response to threats from the French. A second blockhouse, now known as Cromwell's Castle, was built on the other side of the island. In 1651, during the Civil War, the blockhouse was used by Royalists to mount heavy gunfire on Parliamentary forces attacking the adjacent stretch of Tresco's north eastern coastline. It is recorded as still in use in 1750. The blockhouse consists of a gun platform of four unequal sides, which is paved with hard standing on the north west and north east sides for artillery. The platform is defined by a parapet, one metre thick, with splayed openings for guns known as embrasures. The blockhouse was built of randomly coursed granite walling with more regular quoins. A storage chamber, probably for ammunition or gun powder, is built against the south east wall. The blockhouse was defended from landward attack by a single semi-circular rampart around the western and southern crest of the headland's summit. It is visible as an earthen bank up to 10 metres wide and 2 metres high externally. Coastal erosion along the headland east of the blockhouse has revealed mortared walling within deep deposits of blown sand. These are thought to represent lines of seaward defence for the blockhouse. (PastScape)
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This record last updated 26/07/2017 09:22:45

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