Simon Loaring with David Hunt
An island in the vale
A complex network of semi-underground and surface structures, incorporating natural
features, was constructed to resist invasion during the second world war.
A roadblock and pillbox
at Pewsey Defended
Tank Island. (Photos:
Simon Loaring)
Plan of Pewsey
Defended Tank Island
(Simon Loaring)
Britain is scattered with the remains of semi-
underground and surface defence structures that date
from the early years of the second world war. The most
easily recognisable is the concrete mini-fort known
as a pillbox. More than 18,000 were constructed
throughout Britain during 1940, after the War Office
issued a series of standard designs in June of that
year. Although the designs were standardised, a great
number of pillboxes were adapted to fit local terrain
and conditions.
Despite these variations, most pillboxes have a range
of similar features and are squat, heavily constructed
buildings, usually flat roofed and rarely more that
1.98m in height. One or two entrances were included,
covered by a porch or detached wall, along with a
series of horizontal slits called firing loops, loopholes
or embrasures. These slits were sited to provide
interlocking fields of fire with other pillboxes, to
cover an expected direction of attack. The shapes of
the loopholes were designed to minimise external
dimensions while maximising movement internally
for the operator and weapon. Most pillboxes contain
an internal Y-shaped baffle wall to stop ricocheting
The majority of defensive structures built in Britain
to resist invasion during the second world war date
from the period 1940-1941 and were constructed with
the sole purpose of resisting an invading German army
equipped with state-of-the-art armour and artillery.
At the time, military thinking was to use these various
pillboxes in tandem with natural obstacles, to combat
advancing tanks and infantry. The initial defence line
was around the British coast, with further inland
defences organised to form a series of stop lines. The
main General Head Quarters (GHQ) stop line ran
from the south west of England through London and
into Scotland and Wales.
Some elements of the stop lines incorporated
existing features. Others were constructed during the
period. Railway earthworks and waterways were often
incorporated as part of the defences, with concrete
walls constructed along embankments and bridges,
and gullies blocked. Traffic over bridges was impeded
by further walls and concrete anti-tank blocks. Pillbox
lines were integrated with rivers and canals, which
were deepened or straightened to produce anti-tank
barriers. All these systems were integrated by a series
of trenches, blocks, weapon pits, barbed wire and
CONTEXT 109 : MAY 2009
minefields. Where possible, much of the material used
for these structures was carried on canal boats.
During this period, the Kennet and Avon Canal
(codenamed GHQ Line Blue) in southern England
was used as a second line of defence against possible
invasion. A series of pillboxes was strategically located
along the whole length of the canal and concrete
obstructions were placed across canal bridges. This
was especially important as while the tanks in any
German invasion force could move rapidly across
country, their logistic support was in motor vehicles or
even horse-drawn wagons, which needed good roads.
Denial of such crossing points over the line would have
forced the Germans to construct their own bridges,
which would have significantly slowed their advance.
Putting these defence plans into action was a
massive task, not only for the military organisers but
also for the hundreds of civilian building contractors
who worked to complete the defensive network. The
task began with the army commands sending out
teams to survey the countryside and recommend
suitable defence lines. The Royal Engineers were
responsible for the construction and the distribution of
engineering stores, including the miles of barbed wire.
Authority to enter private land came from the
1939 Defence Regulation No 50. This also dealt with
any compensation deemed necessary for the loss of
agricultural value to fields that contained pillboxes
and ancillary features. Orders issued to contractors
typically started with the phrase ‘Provide forthwith
the labour and materials required in the erection
and completion of pillboxes according to drawings…
amendment under the Anti-Tank Defence line RE
Supervising Officers’. A footnote told contractors that
they would be paid according to prices set down in
‘Form of Prime Cost Contract for Emergency Works’,
which they were advised to read and which could
be obtained for the cost of five pence post free. The
cost of building each pillbox varied from location to
location ranging from £48 to £114.
A typical strongpoint or defended ‘island’ site is
visible to this day at Pewsey Wharf in Wiltshire, where a
bridge takes the north-south main road (A345) over the
Kennet and Avon Canal. Here in 1941 the landscape
around the bridge on both sides of the canal was
fortified with a continuous anti-tank ditch, essentially
creating an anti-tank island . The ditch is likely to have
been steep sided, about 14 ft wide and 6 ft deep, and
would have been impassable to German tanks.
The line of the ditch was selected to keep the
enemy away from the bridge and to hold the high
ground, particularly to the south, which was the most
likely direction of attack. The four roads entering
the defended ‘island’ were provided with road blocks
which, in the event of an invasion, could be pulled
across the carriageway to stop all traffic, including
tanks. Four shell-proof infantry pillboxes of the type
FW3/24 were constructed to enable defending troops
to keep the anti-tank ditch and the road blocks under
observation and fire from protected positions .
Each of the Pewsey pillboxes probably contained
a light machine gun and possibly a Boys anti-
tank rifle. Infantrymen would have been dug-in in
trenches around the pillboxes, the bridge and the road
blocks. The pillboxes themselves were constructed
of reinforced concrete, using shuttering to create the
familiar polygonal shape with loopholes. Originally,
timber shuttering was used but due to its increasing
scarcity, cheap porous Phorpres bricks were used
instead and were left in situ. That method saved time
and added a further layer of protection.
All the Pewsey Wharf pillboxes survive intact and
most can be seen easily from the A345 and canal
towpath. In some places it is possible to trace the route
and direction of the ditches on the ground. Two of the
roadblocks survive intact and can be viewed by the
side of the road. It is evident from the position of these
blocks how quickly and easily it would have been to
place them in position.
Most, if not all, of Britain’s wartime defence
structures have been recorded by the Defence
of Britain project, but the number of designated
structures is still quite small. The Kennet and Avon
Canal has a significant concentration of listed
pillboxes, most of them owned by British Waterways
and associated with other listed canal structures such
as bridges and locks. Recent research by volunteers
and British Waterways staff has led to interpretation
of a number of these wartime structures, like those at
Pewsey Wharf. Others are being safeguarded where
possible. An example of this is the anti-tank pillbox
at Tyle Mill, towards the western end of the Kennet
and Avon Canal. This was refurbished in 2006 as part
of a project to upgrade an adjoining boating service
point. The work involved the removal of unsightly
white paint and an infill that obscured the machine
gun loop facing the canal.
The Kennet and Avon defensive structures are for the
most part visible (although a number stand on private
land). Elsewhere, concrete pillboxes, tank traps and
trenches lie hidden or obscured by dense vegetation in
forgotten corners of the land. They represent a part of
our history that is still remembered, and the landscape
is given added meaning by their presence. Now that
the 20th century’s wars and emergencies are long
past, it is essential that the best of these minor, easily
overlooked heritage assets are given due recognition
and are conserved to allow future generations to
appreciate their history and function.
Further reading
Babtie Public Services
Division, Bastions of
Berkshire: pillboxes ofWorld
War II , Royal County of
Berkshire, Reading, 1993
Foot, W, Beaches, Fields,
Streets and Hills: the
anti-invasion landscapes
of England, 1940, CBA,
York, 2006
Hardie, ES, Building
Pillboxes: a personal
story, Loopholes
No 8, online at http://
Lowry, B (ed), 20th
Century Defences in
Britain: an introductory
guide, CBA ,York, 1996
Sanders, I, Pillboxes
UK , online at http://
Saunders, A, Fortress
Britain , Beaufort,
Liphook, Hampshire,
Schellenberg, W, Invasion
1940 , St Ermin’s Press,
London, 2000
Wills, H, Pillboxes: a study
of UK Defences 1940, Leo
Cooper, Trowbridge,
Refurbished anti-tank
pillbox, Tyle Mill, Kennet &
Avon Canal (Photo: Simon
After 20 years experience of
working for various public
sector bodies, Simon Loaring
is a freelance historic buildings
David Hunt, a retired army
officer, is a member of the
Pillbox Study Group.
C O N T E X T 1 0 9 : M A Y 2 0 0 9