Visiting Bletchley Park with Microsoft - Jon Hanna, 2016 .NET MVP

by Jon

IoT Development News

Communicraft's Jon Hanna did us all pround in 2016 in attaining the Microsoft .NET Most Valuable Professional Award 2016 for his work with Communicraft on the .NET framework. Microsoft invited Jon to Bletchley Park as part of the award. He talks about the trip for our blog..


I’m not one for conferences, but when Microsoft held one in Milton Keynes this April I jumped at the chance to attend purely because of where it was hosted; the National Museum of Computing in the grounds of Bletchley Park1, which I’ve wanted to visit since I was a child.

Bletchley Park is a natural home for a computing museum. Positioned half-way between Oxford and Cambridge and quickly accessible from London by road and rail while outside of the main target area of the Luftwaffe, it was chosen to serve as a signals intelligence centre by the Government Code & Cypher School. The efforts of Alan Turing and Max Newman to apply computational theory to automating the task of breaking cyphers led to the Bombe, the Heath Robinson2 cryptanalysis machine and finally to Colossus, the world’s first programmable electronic, digital computer.

The National Museum hosts a rebuilt Heath Robinson but pride of place goes to the rebuilt Colossus, still able to process copies of intercepted messages from the Wehrmacht’s Lorenz cypher machines and determine the settings (the equivalent to a key in modern cryptography) used to create them. Even today the physical speed at which the tape is read is impressive to look at, though the 5,000 characters per second it resulted in is roughly equivalent to the speed of dial-up Internet access, which certainly feels slow to make use of for modern tasks.

Heath Robinson Cryptanalysis Machine
Colossus reading Lorenz SZ (Allied codename "Fish") encrypts at five thousand characters per second

The rest of the museum is an Aladdin’s Cave for computer geeks: Washing machine–sized disk drives with their removable disks just a bit squatter than a spare tyre, memory made from cores of ferrite material (from which we still have the term core dump), a PDP-11 — the computer that ran the first official form of Unix whose architecture still has influence on the Unix, Linux, Windows, OS X, iOS and Android devices we use today.


One of the most bizarre architecturally is the WITCH. Originally the Harwell Dekatron Computer it was built to perform calculations for the nascent nuclear energy programme before becoming the Wolverhampton Instrument for Teaching Computing from Harwell in Wolverhampton University. It used dekatrons — components used for counting in factories that can each hold a decimal digit — for memory and bridged the impedance of binary computing and decimal memory with a special component. It is the oldest computer that is still operational, having been restored but not, unlike the Colossus, fully rebuilt.

WITCH: Wolverhampton Instrument for Teaching Computing from Harwell

As well as preserving the machines, the museum also remembers the people who left an impact on the digital world. One that struck me, perhaps as much because unlike many of the others (Alan Turing, John von Newmann, Grace Hopper, Margaret Hamilton etc.) I wasn’t already familiar with her story, was Dina St Johnson. St Johnson founded the first software company; until then agencies and companies that needed computing could only do so through their own software departments. She invented the industry that we at Communicraft now work in.

While the National Museum of Computing had plenty for the nerd in me to find cool, Bletchley Park itself I found a much more moving experience. They have rebuilt one of Turing’s Bombes (indeed they have two, a real one one that works and a smoke-and-mirrors prop from when The Imitation Game was filmed there), which has the same geeky appeal as the rebuilt Colossus, but the real impact came from walking around the huts and restored offices in which people worked in utter secrecy and gave birth to practical computing as a means to an end of breaking encryption and defeating fascism.

Rebuilt Bombe. Comparing cyphertext with plaintext guesses (“cribs”) it could determine the Enigma settings for that day.
Hut 8. Government Code and Cypher School's codebreaking department. Led by Alan Turing for some of it time.

The historical game of “what if” is a dubious one, but it has been suggested that the work in Bletchley and its outstations shortened World War II by two years. It was the site of great ingenuity, but also a site of sacrifice; safer than the front of course, but still truly arduous.

Windows taped to reduce risk of injury in the case of aerial bombardment, as they would have been during the war.

Those who served there were denied their rightful glory by continuing secrecy for decades to come, and in the case of Turing treated utterly shamefully by the country he had done so much to defend. It is fitting that the site now serves to memorialise their efforts.

“WE ALSO SERVED” — Memorial to veterans of Bletchley Park and its outstations.
Alan Turing OBE FRS. Computer scientist, mathematician, logician, cryptanalyst and theoretical biologist. Inventor of the theoretical Turing Machine and the Bombe.
  1. Though if visiting, note that the National Museum of Computing and Bletchley Park are separate museums with separate entrance fees.
  2. Heath Robinson was a British cartoonist who drew overly complicated machines for simple purposes. Rube Goldberg mined a similar idea later in the US and is better known in some parts of the world.