Former 'Government Communications Radio Station', 309 Gilnahirk Road, Ballyhanwood, Belfast, Co Down, BT5 7SL

Former Government Communications Radio Station, 309 Gilnahirk Road, Ballyhanwood, Belfast

This is a large, sprawling, part two-storey, part single-storey former government office building, built in 1951–52 in a sparse Modern Movement style. It has a brown brick façade and a flat roof throughout, and is now vacant. The building stands on a rise in rural surroundings close to the junction of Gilnahirk Road and Lisleen Road East, just beyond the south-eastern suburbs of East Belfast. Although of limited architectural importance, it is of some interest as a historic link to the Second World War period and the subsequent Cold War.

Layout and Plan Form

The building consists of a largely two-storey front wing to the west, with long single-storey wings of differing size stretching eastwards and linked to one another by a transverse north–south portion. The centre wing is broader than the other two. The south wing appears to have been extended eastwards around 1975–80, affecting the original symmetry of the plan. Note: although the front of the building faces north-west, for the purposes of this description north-west is treated as west.

Exterior: West (Front) Elevation

The front elevation — comprising solely the front face of the west wing — is symmetrical. It is two storeys high with projecting single-storey blocks at either end. The main two-storey portion has a central timber double door with an incised geometric pattern of Greek key-like design. Above this is a squat rectangular fanlight with a metal grille in front bearing a similar pattern to the door. The doorway is framed by projecting concrete piers designed to resemble dressed stone, which support a projecting flat concrete canopy. There is a concrete threshold. To either side of the doorway is a row of six identical metal-framed windows with slender concrete sill and lintel courses.

At first-floor level directly above the doorway is a square window with a bevelled concrete surround and a multi-paned frame with what appears to be toughened, semi-opaque glazing. To either side of this are three very small, widely spaced, almost porthole-like windows — square with curved corners — with concrete surrounds and top-hung multi-paned frames. A flagpole is positioned above the central window. The west faces of the single-storey outer blocks at either end are blank.

Exterior: East (Rear) Face of the Front Wing

The exposed sections of the rear east façade of the front wing could not be seen in their entirety. Internal evidence suggests that the ground-floor level, which is abutted by the three other wings, is blank. The upper level, which could be partly observed from the outside, has a large central projecting bay rising slightly above first-floor level. At the actual first-floor level of the east face of this bay there appear to be three large but relatively squat windows, with three larger windows to the level above. It is possible that this upper level houses water tanks. To both the north and south faces of the bay there appears to be a single large window at first-floor level. To the main wing either side of the bay there are two large windows.

Exterior: South Elevation

The south elevation consists mainly of the south wing, with the south face of the south outer block of the front wing to the far left. This block has three windows matching those at ground-floor front. Also visible is the short south face of the upper floor of the main portion of the front wing, which has one very large window.

The left-hand side of the south façade of the south wing is slightly recessed. It is single storey but with the ground floor set at a relatively high level. To the far left is a timber-and-glazed door reached by a short flight of steps. To the right of this are seven windows similar to those at ground-floor front. Directly beneath these windows is a long lean-to-like structure in corrugated iron, which may have been used as a bicycle or motorcycle shelter. To the right of this, beyond the recessed portion, is a broad high-level window, followed by two plain sheeted doorways with large fanlight-like openings above them.

To the right of this is the section belonging to the extension, probably added around 1975–80, whose brick is a marginally different shade of brown. This portion has a recessed, partly glazed door to the left with three large windows to the right, and a high-level partly glazed doorway — which must at some point have had steps leading to it — between the second and third windows. To the far right the façade is recessed again, with a single relatively small window. The very short east façade of the south wing contains one relatively large window.

Only the left-hand end of the north façade of the south wing is visible externally; it has four large windows broadly matching those at ground-floor front. To the right of these, roughly at the centre point of the wing, it is abutted by the transverse wing. Internal evidence suggests there are no openings to the right of this junction.

Exterior: Central Wing

The central wing is somewhat broader than the south or north wings but roughly the same length as the south wing. The left-hand side of its south face, to the left of the transverse wing, could not be seen from outside, but internal evidence suggests it has no openings. To the right of the transverse wing there are six large windows. This arrangement is repeated in mirrored fashion on the north façade of the wing, with two windows of differing size and a doorway to the shorter east façade.

Exterior: North Elevation

The north elevation consists of the north façade of the north wing with the north face of the north projecting front block to the right. The north façade of the north wing has two windows to the far left, then a small porch projection with a partly glazed door to the east, then a row of seven largely uniform windows. The north face of the north front projecting block has three windows of differing size (one boarded up), a broad doorway that is boarded up but now largely open, and a narrower boarded-up doorway to the far right. The short east façade of the north wing is blank. Internal evidence suggests the south façade is also devoid of openings.

Exterior: Transverse Wing

The left-hand portion of the east façade of the transverse wing — that is, the section stretching between the south and centre wings — has a large window with a much smaller one to its right. The right-hand portion, stretching between the centre and north wings, has two large windows and a much smaller one. The west façade of the transverse wing could not be seen from outside, but internal evidence suggests it has no openings.

Roof and Chimneystack

Although much of the building is single storey, the roof levels are not uniform throughout; for instance, the north wing is considerably lower, as is the east end of the south wing. The building is entirely flat-roofed, the roof surface covered in what appears to be asphalt and interspersed with roof lights. The west end of the central wing has a large gabled roof light. A tall battered brick chimneystack rises from roughly the centre point of the south wing, which contains the boiler house.

Setting and Ancillary Structures

To the north, east, and west of the building there is considerable open space, largely grass-covered, with a broad tarmac drive immediately to the west and a large tarmac area to the east. There is little ground to the south due to the presence of a neighbouring property. Much of the front elevation is obscured by shrub growth. To the north-west of the building is a small single-storey flat-roofed structure in matching brick, possibly a store or electricity generator house. On the opposite side of the main drive to the north-west is a similarly styled security guard's office.

Historical Background

In the late 1930s the GPO established a radio station on this site, initially comprising a few wooden and Nissen huts and an overhead aerial network of cables. The main hut contained 18 banks of American HRO radio receivers. Close by, a Marconi-Adcock direction-finding facility was installed inside an all-metal tank and buried. This work was carried out by the Royal Corps of Signals and the GPO, who provided an underground telephone cable connecting the site to a much larger wartime telecommunications network. The equipment was continually upgraded during the war and had the capacity to intercept all radio transmissions, and in conjunction with one or two other locations in the United Kingdom, to locate the position of any given transmission. Amateur radio operators were enlisted throughout the country to listen to transmissions; when an interesting one was identified, the frequency was handed over to stations such as Gilnahirk. These intercepts were used in the campaign against U-boats in the Atlantic, and coded messages were relayed to Bletchley Park. The station was guarded first by the Royal Ulster Rifles and later by the Royal Military Police.

The current building first appears in a 1952 entry in the valuation book for the area, recorded as 'Government Communications — radio station'. It subsequently functioned as a Ministry of Defence listening post, forming part of the West's Cold War defences under the 'Ultra Intercept' programme. Other listening stations associated with this network included those at Churchill House and Oxford Island, used for both domestic and international intelligence gathering. It is alleged to have continued in this role into the mid-1970s, after which it became a repository for capital tax files. The antennae are now dismantled; in their operational period they formed a spider's web lattice above the building. The vector marks remain in position on the ground. The building appears to have ceased to be used as government offices in the latter half of the 1990s and is now in private hands. The extension to the east end of the south wing is believed to have been added around 1975–80.