World War II codebreaking centre
Bletchley Park is an estate in the town of Bletchley, Milton Keynes (UK).
During WWII, Bletchley Park, or BP for short, was the UK's main
The codes and ciphers of many countries were broken
there, such as messages from the German Enigma,
and the Lorenz SZ-40/42 machines.
It's the place where brilliant people like
and about 12,000 others helped shortening the war by several years .
BP is now a museum that is open to the public every day.
If you are interested in the history of code and ciphers,
BP is well worth a real-life visit.
Many war-time buildings, such as the mansion, the cottage,
the stableyard, H-Block, B-Block and some huts are still
The image on the right shows the Mansion, which is one of the most
prominent buildings on the site. But there is much more to see.
BP has an interesting collection of
cipher machines, such as
Siemens T-52 Geheimschreiber
and much, much more.
TNMOC is an independent trust with its own admission fee and
a separate entrance.
In the past, BP hosted a variety of other museums and collections,
including the Churchill Collection, the Diplomatic Wireless Service (DWS),
the Milton Keynes Model Railway Society, the Toys and Memorabilia Collection
and the re-enactment group 65th Nachrichten Abteilung.
Following a series of reorganisations at the museum, and refurbishment
of several wartime huts, these collections have been discontinued, whilst
the huts have become part of the Bletchley Park Museum.
Visit the Bletchley Park website for the latest information.
- The National Museum of Computing (TNMOC)
Probably one of the largest collections of computers is on display in H-Block,
one of the former war-time buildings. The museum shows the full history of
computing and many of the machines can actually be operated. You will
certainly recognise some old friends here.
TNMOC is a separate entity that is not linked to the Bletchley Park Trust.
It is also the home to the Colossus Rebuild
(see below) and the Heath Robinson Rebuild.
- The Colossus Rebuild Project (H-Block)
Colossus was the first programmable electronic digital computer,
developed at BP during WWII to break the German Lorenz cipher.
After the war, Colossus was kept secret for many years and all
machines were destroyed. In 1994, a team led by
Tony Sale started
the reconstruction of a Colossus. An ambitious task that was completed
in 2006. The machine is now fully operational 
and is part of TNMOC.
- Bombe rebuild project
Another ambitious task carried out at BP is the rebuild of a Bombe;
the machine that was used to break the German Enigma messages during
WWII. Started around 1995 by a team of volunteers led by John Harper,
this task was completed in 2007.
The machine is now operational and is regularly demonstrated
to the public at TNMOC .
- Hut 1 - Diplomatic Wireless Service
Hut 1 was the first hut to be built at BP in 1939. It was initially used by
MI6 for the processing of radio traffic. Between 2001 and 2013 it hosted
the Diplomatic Wireless Service —
a beautiful collection of equipment radio and cipher equipment by David White.
This exhibition is now closed.
- Bletchley Park Post Office
- Bletchley Park Garage
- The Churchill Collection
- Home Front Display (part of B-Block exhibition)
- Maritime Display
- Light Infantry at Pegasus Bridge
- Pigeons at War
- The Projected Picture Trust
- The Toys and Memorabilia Collection
- 65th Nachrichten Abteilung
- Milton Keynes Amateur Radio Society
- Milton Keynes Model Railway Society
In the years following WWII
, the layout of the Bletchley Park site has
changed somewhat. Furthermore, part of the grounds of been sold for housing
development, and the location of the main entrance was moved from Wilton
Avenue to Sherwood Drive, accross the street from the Bletchley railway station.
The map above shows the layout of the Bletchley Park site in 2012.
Click the map for a closer look, or
download it as a PDF here
Block B at Bletchley Park houses one of the most impressive collections
of Enigma machines
in the world. The image on the right shows the
gallery that was opened in 2009. It allows the public to view a variety
of Enigma models from all sides.
There is a standard 3-wheel Enigma I,
a Naval M4,
the famous G-312 Abwehr Enigma,
the commercial Enigma K,
the rare Enigma T
(that was built for the Japanese)
and some special machines that were modified at BP during WWII.
➤ More about Enigma
During WWII, British codebreakers
and Gordon Welchman
developed a mechanical machine, called the
that was used for
breaking German messages created on the famous
Enigma cipher machine.
As none of the original Bombe machines has survived, a team led by
John Harper has built a fully operational replica which was completed
in 2007. The machine is now being demonstrated.
➤ More about the Bombe
During WWII, the Germans used the high-end
cipher machine for messages at the highest level
of OKW, the German High Command.
It was known as TUNNY by the codebreakers.
was the first machine that was built to help
breaking the Lorenz cipher. It was developed by GPO Engineers
Tommy Flowers and Frank Morell.
In 2001, Tony Sale
built a working replica of this machine,
which is now on display at the computer museum (TNMOC)
in Block H.
➤ About Heath Robinson
As the Heath Robonson
machine had a few problems and limitations,
GPO engineer Tommy Flowers
developed and built Colossus,
the first programmable electronic computer.
After the war, all Colossi were destroyed or dismantled.
In 1991, a team led by Tony Sale
started rebuilding Colossus,
using more than 1750 valves. It is now fully operational and
on permanent display at the Computer Museum.
➤ More about Colossus
The National Museum of Computing
Probably one of the largest collections of computers in the world,
is on display in H-Block — one of the former war-time buildings.
The museum shows the full history of computing and many of the machines
can actually be operated. You will
certainly recognise some old friends here.
Note that TNMOC is a separate entity that is not linked to the
Bletchley Park Trust in any way.
It is also the home to the Colossus Rebuild,
the Bombe Rebuild
and the Heath Robinson Rebuild.
➤ More about TNMOC
The name Bletchley Park dates back to 1877, when Samuel Lipscomb Seckham
purchased the estate and built a farm house. Six years later, on 4 June
1883, it was bought by Sir Herbert Samuel Leon (1850-1926) who was a
financier and Liberal MP. He expanded Seckham's farm house with a mixture of
architectural styles into what is now known as The Mansion .
The image on the right shows the mansion around 1908. It was taken from
a Kingsway Real Photo postcard that was date-stamped 8 DEC 1908, which
means that the photograph must be older than that. At that time, the estate
was still owned by Sir Herbert Leon and his wife Fanny.
After Fanny died in 1937, the site was sold to a builder in 1938 and plans
were made for the demolition of the mansion. However, before the site with
its typical mansion was
destroyed, it was bought by Admiral Sir Hugh Sinclair, then Director of Naval
Intelligence and head of MI6.
Bletchley Park was considered a convenient location, as it was within
walking distance from the Bletchley railway station, right at the junction
of the railway lines between Oxford and Cambridge (the Varsity Line) and
the line from London to the north. As we now know, the universities of
Oxford and Cambridge would supply a significant number of code-breakers
during the war.
In order to disguise the true identity of the park, the first government
visitors were announced as Captain Ridley's shooting party.
The Government Code and Cypher School (GC&CS) officially moved to Bletchley
Park (BP) on 15 August 1939, when the first wave of code-breakers arrived.
The rest is history. During the war, some 12,000 people worked at BP, 80%
of whom were women. They were sworn to secrecy and it wasn't until Admiral
book The Ultra Secret came out in 1974,
that some of them started talking about their war-time work at BP.
After the war, the park had various owners and remained in use for several
purposes. It was used, for example, by the General Post Office (GPO),
later British Telecom (BT), Property Advisors to the Civil Estate (PACE) and the
Government Communications Headquarters
(GCHQ, the post-war successor to GC&CS).
The latter closed its training facilities at Bletchley Park in 1987.
By 1991 the estate was largely abandonned and plans were afoot for demolition
of all buildings. On 10 February 1992 however, most of the park was declared
a conservation area by the the Milton Keynes Borough Council. Three days later
the Bletchley Park Trust was established, with the intention to turn the estate
into a museum. This was largely the result of an active campaign by
Tony Sale and a group of interested people.
Finally, in 1993, the museum opened to visitors.
Initially the museum was open to the public every other weekend and the
facilities at the park were limited. There was virtually no carpet and the
roofs of some of the huts were leaking. But it told the fascinating story
of the codebreakers so well. Today, Bletchley Park is turned into a modern
attactive museum with all facilities that you can think of.
And it is open every day.
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© Crypto Museum. Created: Tuesday 14 July 2009. Last changed: Thursday, 21 January 2021 - 09:03 CET.