Cromwell's Castle

Cromwell's Castle

Tresco, Isles of Scilly
TR24 0QE
Tel: (0117) 9750700


Defender of Tresco

Cromwell's Castle is located on the north-west shoreline of Tresco, a mile north-west of New Grimsby, it is a stone 17th century circular artillery tower built by Oliver Cromwell in 1651 as a replacement for King Charles's Castle. which had been built in 1554 on higher ground but proved to be poorly sited and was partly demolished to provide building stone for this later castle. Built on a promontory, to guard the anchorage between Bryher and Tresco, the large three storey tower, supports a platform, pierced by six gun-ports. The guns were mounted on the roof above the garrison's living quarters and magazines. The tower was originally entered at first floor level by an external stair on the south side. The present entrance dates from the construction of the lower gun platform added in the 1740's by Abraham Tovey, Master Gunner. This round tower is one of the few surviving Cromwellian fortifications in Britain.

Royalists had held out on the Isles of Scilly for most of the Civil War period. Increasing tension with the Dutch, and in particular the arrival of a Dutch fleet off the islands in March 1651 demanding reparations from the Royalist privateers based there, prompted Parliament to send Robert Blake, the most successful admiral of the 17th century, to recapture these strategic islands.

The castle was built in 1651, following swiftly on Blake's success, to guard one of the main routes of entry to the heart of the islands and the deep water approach to New Grimsby harbour. It faced a potential enemy with an impossible choice.

No fleet could hope to land troops on this side of Tresco unless it had first destroyed or captured the castle, but the chances of destroying the castle by gunfire from the sea were very slim. The fort was considered worth updating a century later, when a platform for cannon was added on the seaward side.


Overlooking Bryher on the west side of the island.

Opening Times

All Year

Admission Free

Cornish Castles       Isles of Scilly       Tresco       Oliver's Battery       English Heritage in Cornwall