The first attempt at protecting Scilly’s? harbour was Harry?s Walls, named after King Henry VIII and built by Sir John Kiligrew in 1551 and was widely dubbed as a gastronomic waste of the ?6000 of Royal funds, and the castle was to have very little effect as it was never completed. Kiligrew, who already was responsible for the successful ?Pendenis Castle? in Falmouth, had chosen a poor site for this particular addition to the chapter in Scilly’s defences.

The Castle was too far away from the harbour to have any real benefit and also was out of range of the Eastern and Western approaches to the harbour.

A major disadvantage of the Castles? position was that it only protected one half of the town, and the Porth Cressa side, which would later be protected by Star Castle and its Garrison, remained a weakness in the shell of fortification needed to encapsulate Scilly.