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The Bletchley Circle

The Bletchley Circle is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand The Bletchley Circle rather than just read about it. In short: The Bletchley Circle is a television mystery drama series, set in 1952–53, about four women who had worked as codebreakers at Bletchley Park, the principal centre of Allied code-breaking during the Second World War. Dissatisfied with post-war official failure to investigate complex crimes properly, the women join together to investigate for themselves and to bring their findings to the relevant authorities.

The Bletchley Circle — main illustration
The Bletchley Circle — illustration

Key takeaways

  • The Bletchley Circle belongs to computer science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect The Bletchley Circle to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of The Bletchley Circle from memory before moving on to harder problems.

Reference excerpt

The Bletchley Circle is a television mystery drama series, set in 1952–53, about four women who had worked as codebreakers at Bletchley Park, the principal centre of Allied code-breaking during the Second World War. Dissatisfied with post-war official failure to investigate complex crimes properly, the women join together to investigate for themselves and to bring their findings to the relevant authorities. The first series of the miniseries, produced for ITV, was originally shown in the UK in 2012 and premiered in the U.S. in April 2013, on PBS. A second series was broadcast on ITV in January 2014 and on PBS in April 2014. Both series were later aired by Australia's ABC TV. The series was distributed worldwide by Kew Media. The programme was not renewed for a third series. However, in 2018, a spinoff series titled The Bletchley Circle: San Francisco was announced by ITV and BritBox.

Plot Susan Gray, Millie, Lucy, and Jean worked together at Bletchley Park to decipher German military codes for the British military, during World War II. After a brief introduction of the four women at Bletchley during the war, the series begins in 1952, seven years after the war's end, when Susan, Millie, Lucy, and Jean have returned to their ordinary lives. As the story begins, Susan learns about a series of murders that have occurred in the London area and begins to recognise patterns connecting the killings. This inspires her to return to her codebreaking past, and she reaches out first to Millie, and then to Lucy and Jean, after unsuccessfully trying to convince the police to follow up her theory about the crimes. As they all signed orders of secrecy about their work during the war, the two married women (Susan and Lucy), disguise their activities from their husbands as a book club. Failing to secure police involvement, they move from codebreaking and investigation into the realm of field work, with dangerous consequences on several occasions. Scenes of domestic tranquility are contrasted with scenes of the killer stalking and torturing his victims. While initially skeptical about becoming involved, Millie, Jean, and Lucy are convinced to help Susan once they realise the lives of many women are on the line. The series contrasts the conventional but very different lives of the four women and the sense of usefulness they felt while codebreaking during the war. In the Series 1 finale, the women are forced to confront the man they suspect to be the killer.

Cast and characters Anna Maxwell Martin as Susan Gray, a housewife and the mother of two children. She is troubled by the mundanity of her current life. Rachael Stirling as Camilla 'Millie' Harcourt, an independent-minded single woman. She and Susan lost touch when Susan decided to pursue a more conventional lifestyle. Her room becomes the meeting point for the group. Sophie Rundle as Lucy, the youngest member of the circle. She is married to an indolent man named Harry, who beats her when she returns from an investigation. Lucy has an eidetic memory and specialises in recalling and processing data. Julie Graham as Jean McBrian, the oldest woman in the circle, she was a supervisor of the younger women at Bletchley. A librarian after the war, she has many connections and access to information. Mark Dexter as Timothy Gray, war veteran and the husband of Susan Gray. He is unaware of Susan's service as a codebreaker during the war. Ed Birch as Harry, Lucy's controlling husband, who beat her when he suspected her of infidelity after she was attacked. Michael Gould as Deputy Commissioner Wainwright. Also a war veteran, Commissioner Wainwright served with Timothy Gray during the war and now heads the local Metropolitan Police division. Simon Sherlock as DCI Compton Simon Williams as Cavendish. Cavendish was a high-ranking member of the Special Operations Executive who helps Susan by providing information from Malcolm Crowley's personnel file. Steven Robertson as Malcolm Crowley, a disturbed veteran who worked with Cavendish on psychological warfare techniques during the war. Hattie Morahan as Alice Merren (series 2), a former Bletchley Park colleague, awaiting trial for killing John Richards, her old flame and a Bletchley scientist. Jean, believing Alice is covering for someone, begins to reunite the circle to help establish her innocence. Faye Marsay as Lizzie Lancaster (series 2) Nick Blood as Ben Gladstone (series 2), Lucy's colleague and love interest

Episode list

Series 1 (2012)

Series 2 (2014) This series is made up of two 2-part stories totalling four episodes.

Allusions to real events The premise of the series is based on the women who worked at Bletchley Park during World War II, who for the most part did not continue in intelligence work, and under the rules of the Official Secrets Act 1939 in the UK never shared the nature of their contributions to crucial aspects of the Allies' victory. In the second series, one character refers to sarin gas as having been developed by the Germans during World War II, along with other such chemical weapons, then taken up by the former Allies. The UK did have an incident of a young man killed from experiments with the gas in 1953; in 2004, his inquest was reopened, and the cause of death was altered from death by misadventure to death by "application of a nerve agent in a non-therapeutic experiment".

Reception Upon its U.S. premiere—which occurred in prime time following U.S. episodes of Call the Midwife and Mr Selfridge—Variety called The Bletchley Circle "smart, addictive and situated in a fascinating historical moment". In a review of the first series, The New York Times said the series finds "a clever, entertaining way to pay tribute to women who in their time were often overlooked and underestimated, and nevertheless found ways to never be ordinary".

See also Russian remake "Сypher" (Шифр) about former female members of GRU (2019-2024).

References

Further reading "Did the writers get it right?". bletchleyparkresearch.co.uk. 7 September 2012. Archived from the original on 23 June 2017. Discussion of the show's historical accuracy

External links The Bletchley Circle at IMDb The Bletchley Circle at PBS

Worked examples

Example 1 — a first encounter with The Bletchley Circle

Start with the simplest possible case. Write down what The Bletchley Circle claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to The Bletchley Circle before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about The Bletchley Circle ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of The Bletchley Circle

In research
The Bletchley Circle appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses The Bletchley Circle in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
The Bletchley Circle is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2010s British drama television series, 2012 British television series debuts, 2012 English-language television series debuts, so understanding it makes those chapters shorter.
In everyday life
Look for The Bletchley Circle outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study The Bletchley Circle in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what The Bletchley Circle means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain The Bletchley Circle out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is The Bletchley Circle in simple terms?

The Bletchley Circle is a television mystery drama series, set in 1952–53, about four women who had worked as codebreakers at Bletchley Park, the principal centre of Allied code-breaking during the Second World War. Dissatisfied with post-war official failure to investigate complex crimes properly…

Why does The Bletchley Circle matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study The Bletchley Circle?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on The Bletchley Circle.

Tags

  • 2010s British drama television series
  • 2012 British television series debuts
  • 2012 English-language television series debuts
  • 2014 British television series endings
  • 2014 English-language television series endings
  • Bletchley Park
  • British crime television series
  • British detective television series
  • English-language British television shows
  • Fiction about cryptography
  • ITV television dramas
  • PBS original programming

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