St Helen's Fort


Heritage Category: Scheduled Monument

List Entry Number: 1017370

Date first listed: 12-Jun-1967

Date of most recent amendment: 03-Jul-2000


Ordnance survey map of St Helen's Fort
© Crown Copyright and database right 2019. All rights reserved. Ordnance Survey Licence number 100024900.
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This copy shows the entry on 23-Jan-2019 at 18:49:22.


The building or site itself may lie within the boundary of more than one authority.

District: Isle of Wight (Unitary Authority)

Parish: St. Helens

National Park: N/A

National Grid Reference: SZ 64801 89881


Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

The Royal Commission fortifications are a group of related sites established in response to the 1859 Royal Commission report on the defence of the United Kingdom. This had been set up following an invasion scare caused by the strengthening of the French Navy. These fortifications represented the largest maritime defence programme since the initiative of Henry VIII in 1539-40. The programme built upon the defensive works already begun at Plymouth and elsewhere and recommended the improvement of existing fortifications as well as the construction of new ones. There were eventually some 70 forts and batteries in England which were due wholly or in part to the Royal Commission. These constitute a well defined group with common design characteristics, armament and defensive provisions. Whether reused or not during the 20th century, they are the most visible core of Britain's coastal defence systems and are known colloquially as `Palmerston's follies'. All examples are considered of national importance.

St Helen's Fort survives particularly well as a standing structure which retains many of its original fixtures and fittings. Together with contemporary documentary sources relating to the fort, the remains will offer an insight into late 19th century military architecture, engineering practices and strategy as will the adaptation and reuse of the fort in the first half of the 20th century in response to changes in weaponry and tactics.


Legacy Record - This information may be included in the List Entry Details.


The monument includes St Helen's Fort, a circular 19th century Royal Commission sea fort lying in the Solent 1km east of Node's Point. St Helen's Fort was one of a chain of four sea forts in the Solent recommended by the Royal Commission on the Defence of the United Kingdom in 1860 and designed to protect Portsmouth dockyard from seaborne attack. Construction started in 1867 and was completed in 1871.

The fort, which is a Listed Building Grade II, is oval in plan and includes sea bed foundations formed by a ring of cement and brick-filled iron caissons, the area enclosed by which was dredged and filled with poured concrete. Walls of Roche, Portland and Bramley Fall stone were constructed upon the foundations which were 45.7m in diameter, and these in turn formed the base to a superstructure comprised predominantly of concrete. The fort had two internal floors, the lowest of which, the basement level, was reached by a two-level landing stage constructed in 1880 and demolished in 1959 which extended north from the rear of the fort. A series of brick partitions divides the basement level radially into compartments for ammunition and storage, which in turn are divided concentrically by three circular passages. The outermost passage gives access to nine store rooms. Inside this is the lamp passage, which runs around the three magazines, each of which originally lay directly beneath the gun which it supplied and included an ammunition winch. Access to the magazines is via the ammunition passage. Because of the weight of the guns the walls on this level are strengthened with cast iron columns. In the central core is the pump room. Fresh water could be raised by pump from 152m below the sea bed at the rate of 120 gallons an hour, and two water cisterns are situated above the landing stage entrance, either side of which are a further two magazines.

Above the basement is the gun floor, which had provision for three guns, each of which was mounted within a casemate armoured with three layers of five inch wrought iron, separated by iron and concrete. To the rear of these are the soldiers' quarters, consisting of a room for five other ranks and another for one NCO. The roof originally supported a lighthouse and ventilators.

The original scheme was for a fort with 15 guns in casemates, but this was later increased to 17 with the proposed addition of four further guns in turrets mounted on the superstructure. However, uneven settlement of the foundations meant that the size and complexity of the superstructure had to be radically reduced and as a consequence it was recommended that the fort should be fitted with a central two-gun turret with a further gun mounted either side on a Montcrieff mounting. Problems with the latter meant that instead the lower seaward guns on each flank were mounted on turntables, whilst further settling of the foundations in 1878 led to the abandonment of plans to mount a turret. All the emplacements had to be moved to the rear of the fort and in 1880 the turret was replaced by a single 12.5 inch rifled muzzle loader (RML) firing through an iron-shielded embrasure. Two 6 pounder quick firing (QF) guns designed to combat torpedo boats were mounted on the fort's roof in 1900, but removed in 1904. In 1916 two 12 pounder QF guns and two searchlights were installed on the roof when the area became an examination anchorage for the searching of suspicious vessels. During World War II the fort mounted two searchlights in concrete emplacements on the roof and from 1943 a 40mm Bofors gun was installed in the anti-shipping role, specifically to combat E-boats. The Bofors was removed in 1945 and the searchlights sold for scrap in 1957.

All structures, fixtures and fittings associated with the conversion of the fort for recreational purposes and the navigation beacon affixed to the roof are excluded from the scheduling, although the structures to which they are attached are included.

MAP EXTRACT The site of the monument is shown on the attached map extract.


The contents of this record have been generated from a legacy data system.

Legacy System number: 30291

Legacy System: RSM


Books and journals
Cantwell, A, 'Spit Bank and the Spithead Forts. Solent Papers No.1' in St Helen's Fort, (1986), p.27-34
Saunders, A D, 'Fortifications of Portsmouth and the Solent' in St Helen's Fort, (1998), p.142-3
Isle of Wight Council, PRN 1162 - St Helen's Fort,

End of official listing