Old Blockhouse

Old Blockhouse

Tresco, Isles of Scilly
TR24 0PZ
Tel: (0117) 9750700
Email: southwest@english-heritage.org.uk
Web: www.english-heritage.org.uk/visit/places/old-blockhouse


A castle that gave vigorous defence of the Island

Substantial remains of a small 16th century gun tower protecting Old Grimsby harbour, vigorously defended during the Civil War.

The Block House formed part of a series of forts built on the islands during 1550, and followed the attempt to build a large artillery fort, known as Harry's Walls, on St. Mary's.

In fact, the blockhouse did not see action until the 17th century, during the English Civil War. In 1651 a Royalist garrison was defending the islands against attack by a Parliamentarian fleet commanded by the famous Admiral Blake.

Blake attacked Tresco first, capturing its fortifications without difficulty, and then used the island as a base to assault the main Royalist stronghold at Star Castle on St. Mary's. Though vigorously defended, the Old Blockhouse clearly proved of little value against the longer-range guns of Blake’s ships.

It was replaced afterwards by the much stronger gun fort, called Cromwell's Castle, on the other side of the island, though it was still considered serviceable in the 18th century.


About halfway along the eastern side of the island.

Opening Times

All Year

Admission Free

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