ALAN TURING - and His Remarkable Legacy

By Margaret Brecknell

One of the 20th-century’s most brilliant minds, Alan Turing, was born 110 years ago this month. Despite his outstanding contribution to the Allied forces’ eventual victory in World War II and his groundbreaking work in the field of computer science, his achievements were never properly recognised during his lifetime and tragically he died a broken man, aged just 41, at his Cheshire home in June 1954.

Above: Alan Turing Memorial in Manchester Credit: Paul Hermans/ CC BY-SA 4.0

Here is the remarkable story of the mathematical genius whose final few years were spent here in the North-West.

Alan Mathison Turing was born in London on 23rd June 1912. His parents had met and married whilst his father, Julius, was working for the civil service in India, which was still a British colony at the time. Within months of his birth, the couple returned to India, leaving Alan and his brother, John, in Sussex to be cared for by family friends.

At the age of 13, Turing won a place at Sherborne, one of the country’s leading independent boarding schools. For all his later intellectual achievements, Turing’s schooldays were not an unqualified success. He, unsurprisingly, excelled at Mathematics, but, despite his obvious ability, failed to impress his Chemistry teacher because of a tendency to conduct his own experiments rather than those he was instructed to do. According to his later biographer, Andrew Hodges, Sherborne’s then headmaster was moved to write to Turing’s parents that, “If he is to stay at public school, he must aim at becoming educated. If he is solely to be a Scientific Specialist, he is wasting his time at a public school.”

In 1931, Turing won a scholarship to study mathematics at King’s College, Cambridge. At university he had more freedom to develop his own ideas and he began to take a keen interest in the then relatively obscure subject of mathematical logic. After graduating in 1934, he continued to study at Cambridge, attending the lectures of the eminent mathematician, Max Newman, on the foundations of mathematics and was inspired to conduct his own research into probability theory. His dissertation on the subject was considered so innovative that at the age of just 23 he was made a Fellow of King’s College.

For several decades mathematicians had been debating the “Decision Problem”, which was first identified, in 1900, by the German academic, David Hilbert. Hilbert had questioned whether it was possible to design a definitive method whereby any mathematical statement could be proved or disproved. It was this question which Turing set out to research in his dissertation. He concluded that no such procedure existed, using the concept of a hypothetical computing device, now known as the “Turing Machine”, to identify those mathematical propositions which cannot be shown to be true or false.

This original computing machine, although only theoretical in nature, became the basis for the design of the modern computer. He also introduced the concept of algorithms, which remain a mainstay of computer science today. However, Turing was so ahead of his time that it would be another decade or so before advances in electronic technology allowed his concept to become a reality.

Despite his groundbreaking research, Turing initially ran into problems when attempting to have his work published in the Proceedings of the London Mathematical Society. Unbeknown to him, an American mathematician named Alonzo Church had also recently published his own research into the “Decision Problem”, coming to the same conclusion as Turing, but using completely different methods. Turing was compelled to revise his own academic paper so that it included a reference to Church’s work before the London Mathematical

Above: Blue plaque at Alan Turing’s Wilmslow home Credit: Joseph Birr-Paxton/CC BY-SA 3.0

Society finally agreed to publish it. Turing subsequently went to study for his PhD at Princeton University under Church’s tutelage.

The mathematician returned home from the United States in 1938 and in September of that year began to work on a part-time basis for the Government Code and Cypher School (known today as GCHQ). Long before the outbreak of World War II, the Germans had been using a cipher machine called the Enigma to send encrypted messages and thus protect important military and diplomatic communications from falling into the wrong hands. As war in Europe became a reality, the need to crack the Enigma code became ever more pressing. Only days after the outbreak of war in September 1939, Turing took up a full-time role with the Government Code and Cypher School at Bletchley Park in Buckinghamshire.

Bletchley Park had previously served as the family home of a Victorian financier called Sir Herbert Leon. Following the death of Leon’s widow in 1937, the property was acquired by the then head of the British Secret Service, Sir Hugh Sinclair, for use by the Government Code and Cypher School. He is said to have used his own money for the purchase, as Government funds were not forthcoming. Construction of the first wooden huts, which provided additional working accommodation and space for essential facilities such as a staff canteen, began soon afterwards.

Throughout the war Bletchley Park served as the headquarters for Britain’s codebreakers, who were given the unenviable responsibility of finding a way to decrypt the coded messages generated by the German Enigma machine. The codebreaking operations at Bletchley Park remained top-secret. All workers were required to sign the Official Secrets Act on arrival at Bletchley Park and, long after the war had ended, they were still not allowed to disclose even to close family the nature of their secret war work.

Polish mathematicians had previously enjoyed some success in deciphering the Enigma machine’s coded messages. Helped by gaining access to a copy of an Enigma operating manual, they developed an electromechanical machine called the “bomba” which enabled them to find the settings used by the German operators of the Enigma. Shortly before the outbreak of World War II, they shared their work with British scientists. However, the Germans responded by changing their operating procedures and increasing the complexity of the Enigma codes, therefore making them much more difficult to decipher.

Turing set to work to develop an innovative new code-breaking machine called the Bombe, which employed some of the same principles as the Polish “bomba”, but operated in an entirely different and more efficient manner. The prototype was unveiled in early 1940 and the first Bombe, based on Turing’s original design, was installed in Hut 1 at Bletchley Park in March. Later the same year, Turing’s colleague, Gordon Welchman, made an important refinement to the Bombe, improving its overall efficiency still further, and by the end of 1940 Bletchley Park staff were able to decipher within hours German Air Force signals.

Turing also played a pivotal role in cracking the more sophisticated Enigma code, which was used to send messages to the German submarines on active service in the North Atlantic. Time was of the essence, as German U-Boats were successfully targeting in large numbers the North American cargo ships attempting to transport vital food supplies to Britain. Turing was put in charge of the team in Hut 8, the section which was given the responsibility of cracking the German naval code, and developed a new statistical technique called Banburismus. This

enabled certain sequences to be ruled out automatically and led to a much greater success rate in deciphering German naval signals. With this development, it became easier to track the position of the U-Boats in the North Atlantic and provided the large aid convoys with a much better chance of avoiding them.

A similar technique was also employed later in the war to assist in deciphering a new and more sophisticated code which was used by the German High Command to send messages of the highest importance.

The significance of the wartime work undertaken by Alan Turing and his colleagues at Bletchley Park cannot be overestimated, although it remained hidden from the view of the general public, both during World War II and for many years afterwards. It has been suggested that the codebreaking operation may have shortened the war in Europe by around two to three years, meaning that many millions of lives were saved.

Following the end of World War II, Turing resumed his pioneering work in the field of computers. He was recruited by the National Physical Laboratory at Teddington in SouthWest London to design a new type of calculating machine and came up with an idea which was named “the Automatic Computing Engine” (or “ACE”). Turing did not stay at the National Physical Laboratory long enough to see his concept become a reality. He became disillusioned with the length of time it was taking to build a prototype and in 1948 he joined the recently established Computing Machine Laboratory at the University of Manchester.

Turing’s groundbreaking work continued at Manchester. He developed software for the historically important Manchester Mark 1, now acclaimed as one of the earliest computers to store programme instructions electronically in its memory. He also worked on the design for the Ferranti Mark 1, notable today for being the world’s first commercially available general computer.

The success of the Manchester Mark 1 was widely reported in the press at the time and soon a new term, “electronic brain”, was coined to describe the revolutionary invention. A lengthy debate followed on the similarities and differences between the human brain and this new manmade machine.

Turing himself entered the debate with the publication, in 1950, of an academic paper, Computing Machinery and Intelligence in a scientific journal called Mind. Here, he introduced the concept of what has now become known as the “Turing Test”. The test was designed to address the then hotly debated question of whether machines could think. Turing argued that instead of adopting this overly subjective approach to the question, it was more logical to ask if a machine could solve a conundrum which he called the “imitation game”.

At the beginning of the new decade which promised so much, Turing appeared to be at the forefront of the new technological revolution and destined for still greater achievements. Sadly, it did not turn out that way.

In February 1952, Turing was arrested for homosexuality (which remained a criminal act under UK law until as recently as 1967) and was subsequently convicted of gross indecency. He opted to undergo hormonal therapy rather than face the alternative prospect of being sent to prison. He had continued to work on a consultancy basis for GCHQ, but was now required to stop as, with a criminal conviction, he was considered a security risk.

Two years later, in June 1954, Turing died from cyanide poisoning at his home in Wilmslow. He is widely believed to have committed suicide. His death remained largely unreported at the time. The vital contribution made by the Bletchley Park codebreakers to the Allied forces’ eventual victory in World War II did not properly come to light until several decades later and it would also be many years before Turing’s pioneering role in the development of computers became widely known.

Today Turing’s remarkable achievements are finally properly recognised. In June 2001, a statue of the mathematician was unveiled in Manchester’s Sackville Park. The inscription on the plaque at its base describes him as the “Father of Computer Science, Mathematician, Logician, Wartime Codebreaker and Victim of Prejudice”, which seems an entirely satisfactory way of summarising his great achievements. The 2014 film, The Imitation Game, based on Turing’s life, introduced him to a still greater audience.

In 2013 Alan Turing was given a posthumous royal pardon. The official statement concluded that, “A pardon from the Queen is a fitting tribute to an exceptional man”. The British Government subsequently introduced legislation, dubbed “the Turing law”, which enabled other people convicted of now-abolished sexual offences to receive similar posthumous royal pardons. One suspects that Alan Turing would have been especially proud of this legacy.