Details

The monument includes the standing, buried and earthwork remains of a World
War II Heavy Anti-aircraft (HAA) gunsite known as Station H21. The site
includes seven gun emplacements, including one for a Light Anti-aircraft (LAA)
weapon, four gun pits and a command post.

It is unclear exactly when Station H21 was established but it is known to have
been unarmed in June 1942 when the site was mentioned in an Anti-aircraft
Command letter. Guns were often moved from one site to another during the war
and the fact that a site was unarmed at any particular time does not
necessarily mean it had been totally abandoned. The site was probably
connected with the defence of Leeds generally and Yeadon airfield in
particular, the latter of which lies just under 2km to the south.

The Anti-aircraft (AA) guns were used not only for destroying enemy aircraft
but, more importantly, to keep all enemy aircraft at a high altitude and to
deter them from flying on the straight and even course necessary for accurate
bombing. Another important function of AA guns was to indicate the position of
enemy aircraft to their own fighters. Often, when an enemy plane was out of
range, the guns would fire one or two rounds to burst as near as possible,
simply to draw the fighters attention to the enemy. The HAA gun emplacements,
four gun pits and command post are all constructed out of concrete and breeze
blocks and broadly follow standard designs. The four gun pits are arranged in
a semi-circle around the north west side of the command post, with two
unenclosed gun emplacements lying outside the semi-circular arrangement to the
north west and south east. The gun pits incorporate characteristics of both
the March 1938 pattern which were octagonal in plan and had twin axial
entrances, and the DFW 55414 design, which was issued by the Directorate of
Fortifications and Works (DFW) on 10th October 1942 and had a single entrance
and external ammunition recesses and shelters. Both types were designed for
3.7inch guns, although some of the earlier examples were designed for 4.5inch
guns.

The gun emplacements are basically octagonal concrete pads set level with the
ground surface, with a standard ring of holding down bolts for fixing the gun
mounting. The gun pits surrounding four of the gun emplacements are octagonal,
approximately 8m in diameter with 2m high concrete and breeze block walls.
Each gun pit has twin axial entrances which align directly with the command
post. The surrounding walls form three, roofed, compartments on each side of
which the central one leads to a shelter at the rear. On one side the shelter
was typically used as a relaxed duty shelter for the gun crew, the other for
gun maintenance. The other recesses were used for stacking ammunition and
fuses of different, preset lengths.

The LAA gun emplacement, which lies approximately 1m north of the command
post, is brick built and circular in plan, with a wooden beam standing
vertically at its centre and an entrance to the north. The structure is about
2m in diameter with walls that stand 1.5m in height. This is a gun emplacement
for a Light Anti-aircraft (LAA) weapon such as the Lewis gun. Such weapons
were intended for local defence of closely defined targets, principally
against aircraft operating at a height of less than 3000 feet.

The command post is E shaped in plan, semi-sunken and is constructed of breeze
block and concrete with some metal fittings and pipe work surviving. The
bases of various instrument mountings survive in an area at the front of the
building which is enclosed although open to the sky. In operation these
mountings would have housed an identification telescope, the predictor (a
mechanical computer), and height finder. These fed information to the
plotting room, a long room in the covered part of the command post where the
bearing, elevation and range were calculated and relayed to the guns. Other
rooms in the command post acted as offices, stores and communication rooms.
The building faces to the north west so that the Gun Position Officer (GPO),
who was in charge of the command post, could control the firing of the guns,
watch the effects of the fire and take responsibility for the identification
of enemy aeroplanes.

All the buildings and structures, with the exception of the unenclosed gun
emplacements, are surrounded by earth and turf embankments. These would not
only have reinforced the structures but would also help to camouflage the site
from air attack.

The HAA battery complex would, originally, have included a radar platform and
a magazine for storing ammunition. Two structures, one to the south west and
the other to the north east of the command post, were recorded in 1967 on a
1:10,000 Ordnance Survey map, but these no longer survive. Although it is not
certain that the buildings fulfilled these roles, it is likely that they
formed part of the complex.

All modern fences are excluded from the scheduling, although the ground
beneath these is included.

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

Source: Historic England

Reasons for Scheduling

Although of comparatively recent date, 20th century military sites are
increasingly seen as historic survivals representing a defining episode in the
history of warfare and of the century in general; as such they merit careful
record and, in some cases, preservation. One of the more significant
developments in the evolution of warfare during this period was the emergence
of strategic bombing in World War II, and this significance was reflected by
the resources invested in defence, both in terms of personnel and the sites on
which they served. During the war, the number of people in Anti-aircraft
Command reached a peak of 274,900 men, additional to the women soldiers of the
ATS who served on gunsites from summer 1941, and the Home Guard who manned
many sites later in the war. A national survey of England's Anti-aircraft
provision, based on archive sources, has produced a detailed record of how
many sites there were, where they were and what they looked like. It is also
now known from a survey of aerial photographs how many of these survive.
Anti-aircraft gunsites divide into three main types: those for heavy guns
(HAA), light guns (LAA) and batteries for firing primitive unguided rockets
(so called ZAA sites). In addition to gunsites, decoy targets were employed to
deceive enemy bombers, while fighter command played a complementary and
significant role. Following the end of World War II, 192 HAA sites were
selected for post-war use as the Nucleus Force, which was finally closed in
1955.
The HAA sites contained big guns with the function of engaging high flying
strategic bombers, hence their location around the south and east coasts, and
close to large cities and industrial and military targets. Of all the
gunsites, these were the most substantially built. There were three main
types: those for static guns (mostly 4.5 and 3.7 inch); those for 3.7 inch
mobile guns; and sites accommodating 5.25 inch weapons. These were all
distinct in fabric, though they could all occupy the same position at
different dates, or simultaneously by accretion. As well as the four or eight
gun emplacements, with their holdfast mountings for the guns, components will
generally include operational buildings such as a command post, radar
structures including the radar platform, on-site magazines for storing reserve
ammunition, gun stores and generating huts, usually one of the standard Nissen
hut designs. Domestic sites were also a feature of HAA gunsites, with huts,
ablutions blocks, offices, stores and amenities drawn from a common pool of
approved structures. Sites were often also provided with structures for their
close defence; pillboxes are the most common survivals, though earthwork
emplacements were also present. The layout of HAA gunsites was distinctive,
but changed over time, for example to accommodate the introduction of radar
from December 1940, women soldiers from summer 1941, and eight gun layouts
from late 1942.
Nearly 1,000 gunsites were built during World War II, and less than 200 of
these have some remains surviving. However, at only around 60 sites are these
remains thought sufficient to provide an understanding of their original form
and function. This includes 30 of the 192 examples which continued in use
until 1955. Surviving examples are therefore sufficiently rare to suggest that
all 60 well preserved examples are of national importance.

Light Anti Aircraft (LAA) sites used a range of weapons in defence against
lower flying aircraft, and have a particularly wide distribution around the
south and east coasts and close to cities and industrial and military targets
such as airfields. Of all the gunsites, these were the least substantial, with
the fabric depending to a large extent on the type of weapon employed. The
Bofors machine gun was the weapon most frequently provided with a static
emplacement. It was also the only LAA weapon whose associated structures were
covered by formal design drawings, the remainder taking the form of simple
fieldwork dug outs, at most making use of concrete blocks for revetments.
Nearly 1,250 LAA gunsites are recorded as having been built during World War
II and can be accurately located. Around 50 of these have some remains
surviving, though at only around 40 sites are these thought sufficient to
provide an understanding of their original form and function. Surviving
examples are therefore sufficiently rare to suggest that all 40 examples are
of national importance.

The Anti-aircraft gunsite, 260m east of Carlton Hall, is a particularly well
preserved example of an early to mid-World War II gunsite. It retains the
functional core of the station, the command post, gun emplacements, including
one for a LAA weapon, and gun holdfasts.

Source: Historic England

Sources

Books and journals
Dobinson, C, 'Anti-invasion Defences of WWII' in Twentieth Century Fortifications in England, (1996), 112-152
Other
Roof Over Britain The Official Story of Britains AA Defences 193, (1945)

Source: Historic England