Bletchley Park
Fifty miles (80km) north-west of London
lies Bletchley Park. In 1883, it became home
to the Leon family, whose patriach was a
wealthy City of London financier. Herbert
Samuel Leon bought over 300 acres of land
beside the London and North-Western Railway
line that passed through Bletchley, Buckinghamshire,
developing sixty of those acres into his
country estate. At the heart of the estate,
he built a mansion in a curious mixture of
architectural styles. One of Bletchley's
greatest benefactors, he was much loved by
the local people. He was awarded a baronetcy
in 1911.
Following the deaths of Sir Herbert and
Lady Fanny Leon, the Park fell into the hands
of property developer Captain Hubert Faulkner,
who intended to demolish the buildings and
sell the land as a housing site.
But the Government was about to intervene.
It was 1938 and the threat of war loomed
as Hitler invaded first Austria and then
Czechoslovakia. The Government Code and Cypher
School, then based in London, needed a safer
home where its intelligence work could carry
on unhindered by enemy air attacks. At a
junction of major road, rail and teleprinter
connections to all parts of the country,
Bletchley Park was eminently suitable.
Commanded by Alastair Denniston, the Park
was given the cover name Station X, being
the tenth of a large number of sites acquired
by MI6 for its wartime operations.
After meticulous preparation
and a series of trial runs, the codebreakers
arrived in earnest in August 1939.
They masqueraded as ‘Captain Ridley's
Shooting Party’ to disguise their true identity.
It was to be the first instalment in one
of the most remarkable stories of the Second
World War.
Enigma
The Enigma cypher was the backbone of German
military and intelligence communications.
Invented in 1918, it was initially designed
to secure banking communications, but achieved
little success in that sphere. The German
military, however, were quick to see its
potential.
They thought it to be unbreakable, and not
without good reason. Enigma's complexity
was bewildering. Typing in a letter of plain
German into the machine sent electrical impulses
through a series of rotating wheels, electrical
contacts and wires to produce the encyphered
letter, which lit up on a panel above the
keyboard. By typing the resulting code into
his own machine, the recipient saw the decyphered
message light up letter by letter. The rotors
and wires of the machine could be configured
in many, many different ways. The odds against
anyone who did not know the settings being
able to break Enigma were a staggering 150
million million million to one.
The Poles had broken Enigma in 1932, when
the encoding machine was undergoing trials
with the German Army. They even managing
to reconstruct a machine. At that time, the
cypher altered only once every few months.
With the advent of war, it changed at least
once a day, effectively locking the Poles
out. But in July 1939, they had passed on
their knowledge to the British and the French.
This enabled the codebreakers to make critical
progress in working out the order in which
the keys were attached to the electrical
circuits, a task that had been impossible
without an Enigma machine in front of them.
Armed with this knowledge, the codebreakers
were then able to exploit a chink in Enigma's
armour. A fundamental design flaw meant that
no letter could ever be encrypted as itself;
an A in the original message, for example,
could never appear as an A in the code. This
gave the codebreakers a toehold. Errors in
messages sent by tired, stressed or lazy
German operators also gave clues. In January
1940 came the first break into Enigma.
It was in Huts 3,6,4 and 8 that the highly
effective Enigma decrypt teams worked. The
huts operated in pairs and, for security
reasons, were known only by their numbers.
The codebreakers concentrating on the Army
and Air Force cyphers were based in Hut 6,
supported by a team in the neighbouring Hut
3 who turned the decyphered messages into
intelligence reports. Hut 8 decoded messages
from the German Navy, with Hut 4 the associated
naval intelligence hut. Their raw material
came from the 'Y' Stations: a web of wireless
intercept stations dotted around Britain
and in a number of countries overseas. These
stations listened in to the enemy's radio
messages and sent them to Bletchley Park
to be decoded and analysed.
To speed up the codebreaking process, the
brilliant mathematician Alan Turing developed
an idea originally proposed by Polish cryptanalysts.
The result was the Bombe: an electro-mechanical
machine that greatly reduced the odds, and
thereby the time required, to break the daily-changing
Enigma keys.
Postwar
With the declaration of peace, the frenzy
of codebreaking activity ceased.
On Churchill's orders, every scrap of 'incriminating'
evidence was destroyed. As the Second World
War gave way to the Cold War, it was vital
that Britain's former ally, the USSR, should
learn nothing of Bletchley Park's wartime
achievements.
The thousands who had worked there departed.
Some continued to use their remarkable expertise
to break other countries' cyphers, working
under a new name: the Government Communications
Headquarters (GCHQ).
The site became home to a variety of training
schools: for teachers, Post Office workers,
air traffic control system engineers, and
members of GCHQ. In 1987, after a fifty-year
association with British Intelligence, Bletchley
Park was finally decommissioned.
For decades, the codebreakers would remain
silent about their achievements. It was not
until the wartime information was declassified
in the mid-1970s that the truth would begin
to emerge. And the impact of those achievements
on the outcome of the war and subsequent
developments in communications still has
not been recognised fully.
See also Jewish
Personnel at Bletchley Park in World War
Two
Sources: Bletchley Park National
Codes Center |