During WWII there were a number of Radio Direction Finding
(RDF) sites in Shetland. Some of these sites were to be later called Radar
units after the name was introduced by the US Navy and the US entered the war.
The Chain Home, Chain Home Low, Naval
Coastal Defence U-boat and Army Gun Laying sites all became known as having
Radar equipment. However, there were a number of other sites which used RDF
principles, often referred to as "listening posts" or, more simply,
as Direction Finding (D/F) units. Some of these D/F units will be discussed in
this article.
The nature of the work was highly classified and few
personnel were attached to each unit - these factors have led to there being
little information readily available about this subject. When researching some
of the locations most information has been gleaned from the foundations which
remain long after the war and from a few contemporary anecdotes - much of the chronology and the roles
of these units has had to be assumed. I have also been fortunate to receive
assistance from a number of helpful individuals. There may well be other locations in Shetland
I have not discovered and I am no expert in the technology involved. I hope
this article encourages people with more details to get in touch.
The roles of the units varied with some of them having more
than one purpose. Some were designed to be "listening posts "- just
to monitor enemy transmissions, others were used for the detection and location
of enemy assets (submarines, surface shipping or aircraft). A few sites worked
as "beacons", transmitting signals to help allied aircrew to
determine their location, eg after bombing missions. when accurate information
was sometimes needed to help recovery to airfields. In Shetland these D/F units
were intended to work in the Medium Frequency, High Frequency or Very High
Frequency Bands (MF = 300kHz to 3mHz, HF = 3MHz to 30MHz and VHF = 30MHz to 300MHz). As a general rule the
lower the frequency the longer the antenna required. I will deal with the units I have researched
by Frequency Band and, because of software limitations, I have had to issue the
article in 2 parts. This section covers
the Medium and High Frequencies:
Medium Frequency
(MF) Sites.
I have visited two MF sites, both just north of Sumburgh
Airfield at the south of the Shetland Mainland, one belonging to the Air
Ministry and the other to the Admiralty.
Both of these sites required 4 masts, each of them probably 70' tall, to support their antenna.
The lower part of each mast would have looked similar to that in this picture
from Stan Ames.
Air Ministry MF Site: The picture below has been taken
from Zoom Earth and, for clarity, I have marked the positions of the mast bases
with yellow circles:
The next picture is an enlargement of the westerly mast base
and indicates the anchor points for its cables:
Each anchor point looked like this:
There is little of the site left to see except foundations :
Thanks to Cecil Duncan for the information that this unit
was staffed by civilians seconded to the Air Ministry. The late Andrew Halcrow from Walls in Shetland was recruited
by MI5 at the beginning of WWII to join a small unit initially called the Radio
Security Service. A few amateur radio enthusiasts with advanced Morse skill
were selected for this service and they became known as Voluntary Interceptors.
During the war Andrew spent some time on the UK mainland and in Orkney He also
spent some time at the Air Ministry DF station at Ward Hill. The following
picture, also kindly provided by Cecil Duncan, shows a civilian operator at
work on Ward Hill:
An interesting feature of this picture is the equipment by the wall beyond the civilian. Behind his head is a T 1154
wireless transmitter set and lower down the corner of a R 1155 receiver can
just be detected. This equipment was normal wireless equipment in the standard
RAF WWII heavy bombers such as the Lancaster. Clearer images of the T 1154 and R
1155 wireless equipment can be seen in these photos from Bob Jenner:
Later Andrew was awarded the Imperial Service medal for his
radio work, as can be seen in this press cutting - also provided by Cecil Duncan:
Because there was a
transmitter in the Operations Hut I believe it likely that this site may
have provided homing information to the crews of aircraft which had been
engaged against axis targets or, possibly, for relaying messages to and from
these crews.
The second MF direction finding site
about which I have some information lies about 1 km NE of the Air Ministry site
- at a place called Aipleton.
Admiralty VP No A4105 Sumburgh Special W/T Stn
Admiralty VP No A4106 Sumburgh - Ward Hill Special W/T Stn
(VP = vulnerable point, requiring
special guarding and W/T stands for wireless telegraphy)
In the following paragraphs I will discuss the
Aipleton MF element - the HF unit will feature later. Fortunately, in 2015 I was lucky to meet Geordie
Mainland who, as a teenager, worked on the site. Although in his 90's when I
met him Geordie had a cheerful character and an excellent memory and I am
indebted to him for some of the information below. Geordie had previously taken
part in the construction of two Admiralty radar sites on Fair Isle and, when at
Aipleton, his main role was as a messenger - delivering coded intercept messages
to the Shetland Naval HQ in Lerwick.
From Lerwick the coded messages were forwarded to Bletchley Park for deciphering. Bletchley Park, just NW of
London, was the home of the UK's WWII code breakers. Geordie was equipped with
a khaki painted ex-Automobile Association BSA M20 500cc motor bike.
The
Aipleton MF site had more than one receiver , though possibly no transmitter - it's
specific role was intercepting & monitoring axis transmissions. Because the UK was unable to produce enough receivers of the right type an order was placed foe American equipment and numerous HRO sets were obtained - originally brought out for the Ham radio market in about 1935. There is a story that the HRO stood for "Hell of a Rushed Order". The set was manufactured by the National Radio Company of Malden, Massachusetts - thanks again to Cecil Duncan for the photo.
The unit was Operational from August 1939 until the end of the war. One of the Radio Operators at this site during the war was the late Fred Barlow, a civilian from Heywood in Lancashire. He had been a sub-postmaster at a telegraph sub-post office in Blackpool before the war. His wartime "Certificate of Employment" described him as a Civil Servant employed by The Admiralty. The Certificate also stated that he was performing "Essential Services in War". The picture below, taken from an Identity Card, shows what Fred looked like during this period:
The unit was Operational from August 1939 until the end of the war. One of the Radio Operators at this site during the war was the late Fred Barlow, a civilian from Heywood in Lancashire. He had been a sub-postmaster at a telegraph sub-post office in Blackpool before the war. His wartime "Certificate of Employment" described him as a Civil Servant employed by The Admiralty. The Certificate also stated that he was performing "Essential Services in War". The picture below, taken from an Identity Card, shows what Fred looked like during this period:
At Aipleton Fred had to work long shifts and was not too keen
to have to share his "digs" with someone else who was on shift at different
periods from himself, but accommodation was in short supply. He mentioned getting away from his workplace with some of
his workmates using a motor-cycle and sidecar, quite possibly the same vehicle
entrusted to Geordie Mainland. On his trips home to Blackpool, where his wife
had taken over his sub-post office duties, he took parcels of unrationed food, which
seemed to be more readily available in Shetland. Fittingly, Fred is mentioned on the Bletchey Park Roll of Honour.
The unit was operational and the
equipment was active during the hunt for the German pocket battleship Bismarck
(Apr/May 41). One of the stations aims was to attempt to get a bearing on enemy
radio transmissions so that the information, together with similar information
from other sites, could be used to "fix" the position of enemy
surface ships and U Boats by triangulation. The other aim was to record enemy transmissions
and to forward the coded signals to higher authority. The speed of analysing
this information was important - hence the need for Geordies motor bike!.
The aerials were situated about
1km NE of the Air Ministry establishment and about 1km east of the main Lerwick
to Sumburgh road. There was a billet, probably for some of the Admiralty/civilian personnel and a
building for storing fuel, approximately 3 or 400m west of the operations/mast
area.
The 4 masts were laid out in a
similar fashion to those at the Air Ministry unit, each mast having 4 cable
guying points:
The operations hut was located
within blast walls and the site powered
by petrol powered generators.
The MF site was manned 24 hours a
day by a watch of 3 or, possibly, 4 people.
The small, brick-built building to the south of the billet, had a metal door and was almost certainly used to store petrol for the generators and vehicles:
The small, brick-built building to the south of the billet, had a metal door and was almost certainly used to store petrol for the generators and vehicles:
According to Geordie Mainland,
the Commander of the site was "ex Navy", possibly an ex Swordfish
gunner, who had a French sounding name.
With all the secrecy surrounding
this site it is impossible to say how successful it was in providing useful
data but, according to Geordie Mainland, the unit continued operations until
the end of WWII.
High Frequency
(HF) Sites.
There are 2 WWII H/F sites in Shetland that I have looked at closely and, possibly, a third that I was recently informed of, but I suspect that there may have been
others. The 2 sites I have examined are
at Aipleton, north of Sumburgh, close to the Admiralty MF site, and on Crussa
Field in Unst. Before discussing more details of each site it will be simpler
to describe the similarities between the sites. There were a number of types of
HF D/F equipment in use by the Allies during WWII but the Aipleton and Crussa
Field units were basically alike. Most D/F sites used "Adcock
Antenna" which consisted of 4
masts, equidistantly spaced in the form of a square. Each mast held an antenna,
the size being dictated by the frequency used - the lower
the frequency, the taller the masts. The
two MF sites operated in the range 300 kilohertz to 3 megahertz and required
tall masts. The 2 HF sites discussed in this section would have worked in the
frequency range 3 megahertz to 30 megahertz and therefore needed much smaller
masts, about 30' in height .
The HF sites at Aipleton & Crussa Field appear to have been equipped with Marconi DFG. 24 Direction Finding sets. Operations were conducted from smaller huts which had no protective blast walls. A typical war time HF unit, similar to the establishments at Aipleton and Crussa field, is shown in the following picture:
The HF sites at Aipleton & Crussa Field appear to have been equipped with Marconi DFG. 24 Direction Finding sets. Operations were conducted from smaller huts which had no protective blast walls. A typical war time HF unit, similar to the establishments at Aipleton and Crussa field, is shown in the following picture:
Each unit would possibly have had 4 personnel working watches, one man
on duty at a time. Both huts would have required power from an outside source and have had the means to pass on
significant data rapidly (phone/radio). Apart from a receiver the hut would
have been equipped with an item called a goniometer, like the large, circular
display near the centre of the next picture, which was taken in England during
1943:
Now to look at the Aipleton HF
site specifically:
Aipleton HF. The
foundations of this unit are a short distance north of the MF site and, at ground
level, they can be difficult to locate. The HF equipment used power from the
generator/s within the MF site blast walls. In places it is just possible to
see where the power cable trench was dug and, although it may mean leaping a few drainage
ditches, it is possible to follow the route which can be seen faintly in the
Zoom Earth image below:
The remains of the foundations
look like this:
and each mast base looks
similar:
When the site was constructed 4
x trenches were dug radiating from the hut in approximately N,S,E & W
directions. Copper tape and/or wire was laid in these trenches to provide
screening to help amplify the radio signal (or possibly just for earthing).
The establishment was closely
associated with the MF site and some of the personnel possibly shared the same billet. According to Geodie Mainlland the hut was usually inhabited by one person at a
time and Geordie did not relish approaching it to deliver or receive messages,
especially during the hours of darkness. The single occupant was armed with a loaded
revolver and always drew the weapon before opening the locked door to see who
was outside.
With the secrecy which
surrounded such units it has not been possible to discover any official
accounts detailing the specific work carried out from the site
Crussa Field, Unst HF.
The layout
of this unit was very similar to the one at Aipleton just described. However,
Aipleton was controlled by the Admiralty, whereas, this unit came under the Air
Ministry. It was situated on Crussa Field to the NW of Baltasound and just SE of
the archaeological site known as the Rounds of Tivla. Once again, as with
Aipleton, I was fortunate enough to talk
about the site with someone who had actually seen it when it was operational.
The late Eileen Hunter of Baltasound was just a child about 7 years of age when
she visited the hut but, luckily, Eileen was possessed of a marvellous memory. Four of the RAF personnel who worked on the
Unit were actually billeted at Eileen's family home, Milbrae at Baltasound and
she remembered their names. They were: Leslie Sessions, Larry
Perkins, Tony Hunter and W.E. (Gerry)
Gerrard. Gerry Gerrard returned to Uns t on holiday after the war. He was a commercial
artist in civvy street and was known to be quite a character - a copy of one of
his sketches below:
The remains of the HF site are
not as well preserved as those at Aipleton, possibly because (according to
Eileen Hunter), it was only operational for about a year (perhaps in 1943 or
1944).
The places where the 4 masts
were situated can still be seen and the base for each of them looks like this:
From the Rounds of Tivla side
the site looks like this:
Eileen remembered the Hut as
small and manned by one person at a time. She was able to recall a single chair
and a table with some kind of electrical equipment on it. Part of the
electrical equipment included a circular display - this was likely to be a goniometer,
similar to the early model seen in the following picture:
Goniometers were used for measuring the azimuth or elevation angles of
radio transmissions from a receiver. I found no evidence of the communications
system used from the site. It was possibly a telephone, with the cable buried
close to the site to help prevent possible interference to the DF equipment. Power to the equipment would have been
provided in one of two ways; either, a portable lightweight, petrol fuelled generator
would have been placed near to the site or, a heavier diesel engine would have
been located further from the equipment
and a cable laid to the top of Crussa Field.
I have heard stories that the remains of a WWII generator bed
lie under what appears to be a white roofed building marked in the next picture, in which case a
cable would have to have been laid about half-a-mile up to the hut:
Two generator beds (for comparison) near a DF site on Whalsay:
The purpose of the HF
site on Crussa Field is not obvious to me and I have no official data on the
subject. Being an RAF unit could
indicate that it may have been used to act as a "beacon" to
assist in the recovery of allied aircraft which had been engaged in operations
over Norway or on long Coastal Command sorties. If it were used for obtaining
information on German aircraft bearings an efficient and rapid system of
communication would have been required
so that, when combined with bearings from other sites, expeditious data
on those aircraft positions could be calculated.
Lerwick MF or HF
This DF site I had not heard of until recently
when I was sent the photo below by Cecil Duncan. The photo is held in the
Shetland Museum and shows an Air Ministry site just to the NW of Lerwick:
It looks as if the larger mast in the
middle is a standard 90' timber tower, frequently used by the RAF. It appears
to be in the centre of 4 shorter masts, each at the corner of a square. Each of these masts seems to be a
single pylon, perhaps 50'' to 80' in height. I have been to the area once (on a cold and
very windy day) but little remains apart from one building and some
foundations. So far I have found no traces of the mast bases:
I have yet to establish the purpose
of the site and would welcome information from anyone who can help. At a guess,
I would suggest the 4 pylons were part of an MF or HF DF system of a different type
to the Crussa Field and Aipleton sites but still using an Adcock aerial layout.
The single 90' tower is of the type that the RAF used for VHF communications,
so it is possible that the unit was capable of both MF or HF and VHF operations. I
will add more information if, or when, it becomes available.
The second part of this article discusses 3 possible Very
High Frequency DF sites:
https://ahistoryofrafsaxavord.blogspot.com/2019/02/some-wwii-direction-finding-sites-in_28.html
https://ahistoryofrafsaxavord.blogspot.com/2019/02/some-wwii-direction-finding-sites-in_28.html
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