Buildings Nos 31, 35 and 37 (Seaplane Sheds) and Winch Houses, former HMS Daedalus

Summary

Three paired Admiralty Type ‘J’ seaplane sheds and associated winch houses, circa 1917-18.

Reasons for Designation

Three paired Admiralty Type ‘J’ seaplane sheds of and associated winch houses, circa 1917-18, are designated at Grade II for the following principal reasons:
* Date and rarity: a rare survival of a group of WWI seaplane sheds with associated winch houses, believed to be the only surviving examples of Admiralty Type J hangars nationally;
* Architectural interest and intactness: the seaplane sheds survive in remarkably intact condition given their vintage. Inevitable re-cladding, replacing the original asbestos-cement sheeting, has not been to the detriment of the legibility of the structures with their original frames surviving intact;
* Historic interest: a group of key buildings from the HMS Daedalus
site which was one of only 26 seaplane stations nationally built to provide an airborne coastal defence during WWI. Daedalus was a significant naval seaplane training school and was initially developed as a satellite to the Royal Naval Air Service base at Calshot, on the opposite (west) side of Southampton Water, and which retains the most significant group of early seaplane hangars nationally (Grade II*). Daedalus was also a very significant operational naval flying base during WWII;
* Group value: the seaplane sheds and their winch houses form a coherent group of early (1917-18) buildings around the former slipway to the sea.

History

Although unofficial use by aircraft seems to have been occurring here as early as 1915, it was in 1917 that the site later known as HMS Daedalus was established as a temporary naval seaplane training school. This was first developed as a satellite to the Royal Naval Air Service base at Calshot, on the opposite (west) side of Southampton Water. The temporary base occupied 30 acres of requisitioned land (including a number of Victorian houses) with a series of temporary wood and canvas hangars. Initially the aircraft were transported down to the sea on rails.

From November 1917 when the base became permanent, permanent structures including hangars and slipways were constructed. In April 1918 the RAF (formed that month with the merger of the Royal Flying Corps and Royal Naval Air Service) took over its administration, the site becoming known as No 209 Training Station, training not only British but also foreign pilots. By 1918 a staff of nearly 500 provided training to students in around 70 seaplanes. In the 1920s training continued for the newly-formed Fleet Air Arm, training pilots for warships and later armed merchant cruisers in the Battle of the Atlantic.

The seaplane hangars were amongst the earliest structures erected on the site, located to the north-west and south-east of a generous concrete apron and connected by concrete slipways to the sea. Their precise date is uncertain (late 1917 or 1918) but one Lt J G N Clifts is known to have been responsible for a number of buildings on the site from 1918, including the Power House. The whole base is closely woven into the adjacent suburban roads, houses predating 1917 being either demolished or reused - the most notable amongst these being Westcliffe House - a characteristic example of how early seaplane bases requisitioned earlier properties for use as officers' messes.

A major rebuilding was undertaken after 1931 when the base became Coastal Area HQ. The most architecturally distinguished building relating to this phase is the handsome officers' mess which fronts onto a large grassed area to its south. This is bounded on its south-east side by a group of married quarters in the Garden City style characteristic of RAF expansion up to 1934. To the north is the station guardhouse (a 1926 design), institute and barracks square of 1932-5.

By 1939 Lee-on-Solent was a very important naval flying site including for operational squadrons. Further additions in 1939 included the H-plan barracks blocks and Eagle Block, which served as HQ of Coastal Command until August 1939. When the Fleet Air Arm was transferred to the Admiralty in May 1939 the Lee-on-Solent site was renamed, as was traditional, in the form of one of His Majesty’s Ships and became HMS Daedalus. The site was attacked twice during WWII because of its strategic importance.

Post-WWII the site contracted although continued in its training role (including helicopter training) but also with an engineering component (such as Hovercraft testing). It was also the base for Air Sea Rescue before closing in 1996.

The site is located immediately adjacent to the Solent, but is now severed from it by a road (Marine Parade).

Details

Three paired seaplane storage hangars of circa 1917-18 known as buildings 31, 35 and 37. Two, Buildings 31 and 35, are located either side (to the north-west and south-east respectively) of the former slipway and have associated winch houses to winch the planes up and down the slipway. Building 37 is located at right-angles to the other hangars and is the south-easternmost of the group.

MATERIALS: steel framework and roof trusses, corrugated steel cladding and roof covering replacing (and therefore not of special interest) the original asbestos-cement cladding. Steelwork by Frodingham Iron and Steel Co. Ltd.

PLAN: end-opening coupled hangars, each shed of 14.6m (48') span and in 5 bays, each of 3.6m (12'). At the inner end of each pair, facing a broad concrete apron, two gables above full-height pairs of sliding doors, giving maximum half-width opening. Two pairs are located on the south-west perimeter of the site adjoining Marine Parade, and originally separated by twin slipways, now one, down to the water's edge. The third pair is at right angles to these, at the south end of the apron.

EXTERIOR: towards the apron each couple has twin gables over paired sliding doors. In the long flanks, set low, the original design included a series of 5 multi-pane steel casements, with similar casements to the outer gables. Most have not survived the re-cladding, the exception being Building 35 which retains two steel-framed windows in its south-east elevation and one in its south-west elevation (two other windows to this elevation are wooden framed and are later additions; a further two windows here are boarded up but given their size are likely to be wooden framed also). To the south-east of building 31 is a restored winch house for hauling planes out of the water. This is a simple gabled building of brick which originally had a slate roof, now with corrugated sheet covering (the covering is not of special interest). It has a pair of timber double doors beneath a heavy concrete lintel in the end gable facing onto the slipway and a casement window with similar lintel in the north-east elevation, also a fixed window to the south-west.. A further brick winch house is located to the north of building 35 but has been altered as it is now flat-roofed and has had its gable-end door narrowed.

INTERIOR: original steel trusses, frame cross-bracing and portal framing to the front including original rails for the sliding doors. Modern insertions are not of special interest.

Sources

Books and journals
Gosport Borough Council, , Daedalus Conservation Area Appraisal, (2007)

Websites
HMS Daedalus Heritage: Early Days 1917-1920, accessed from www.fleetairarmarchive.net/daedalus/History_WW1.html

Other
English Heritage, Thematic Study of Military Aviation Sites and Structures , 2001,
Gosport Aviation Society, An Aviation History of Gosport, 1991,

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