ELSIE at South Eastern District Office London, 1959 © Royal Mail Group, courtesy of The Postal Museum

WHENEVER there is mention of Bletchley Park and its codebreakers, one name instantly springs to mind: Alan Turing. The brilliant mathematician and computer scientist has latterly quite rightly been acknowledged for his work during the Second World War.

But among the many talented men and women working for and at Bletchley there was another brilliant man whose name is perhaps less familiar: Tommy Flowers.

He would lead the design and building of Colossus – the world’s first programmable electronic computer – which helped to solve encrypted German messages. Eventually, 10 Colossus machines were built and they provided vital intelligence for the military which historians believe helped to shorten the war.

Tommy Flowers. Courtesy The Postal Museum

Today, the official site for GCHQ describes Flowers as “a visionary”. Now a new exhibition at The Postal Museum, Sorting Britain: The Power of Postcodes, which looks at the history of the postcode, is also shining the spotlight on the work of among others, Flowers.

Born in 1905 in Poplar in London’s East End to a bricklayer father, Flowers was an apprenticeship mechanical engineering when he took evening classes at the University of London for a degree in electrical engineering.
In 1926 he went to work at the telecommunications branch of the General Post Office (GPO). Then in 1930 he was employed at the Post Office Research Station at Dollis Hill in north west London.

It was here that his director (William) Gordon Radley suggested Flowers when Turing asked for help at Bletchley Park. Turing was impressed with Flowers’s work and introduced him to fellow codebreaker Max Newman, which eventually led to the creation of Colossus.

But only after a tussle. The powers that be at Bletchley Park were not keen on the idea.

There were also suggestions of snobbery with one account suggesting that Flowers’s working-class background and East End accent set him apart. So instead, Flowers went about building Colossus at Dollis Hill, having to use some of his own money to make it happen.

While the government eventually awarded him a £1,000 payment, this did not cover his outlay. And in any case, Flowers is said to have shared the money with those who had worked with him on Colossus.
Flowers, who had been made an MBE in 1943, went back to his “day job”.

Recalling his time working for Bletchley Park he said: “It was a great time in my life. It spoilt me for when I came back to mundane things with ordinary people.”

Nevertheless at Dollis Hill there were yet more developments and innovations to come.

Mount Pleasant Sorting Office Letter sorting by women c.1914 © Royal Mail Group, courtesy of The Postal Museum

Flowers and his team worked on all-electronic telephone exchanges which led to the Highgate Wood telephone exchange. He was “loved by his team”, according to Dame Stephanie Shirley who was also at Dollis Hill. He spoke to everybody exactly the same irrespective of their “status” or gender, she recalled.

Flowers was also involved in the development of ERNIE – the famous machine that generates the numbers for the Premium Bonds.

But it will be another impressive machine, ELSIE, that greets visitors to The Postal Museum exhibition. One of the only original 1950s Electronic Letter Sorting Indicating Equipment left in existence, it will be on display for the first time in 20 years.

A hearing aid will be part of the exhibition too, as its invention was a result of work to improve telephone quality.

The Postcode Song by Kerry – featuring Poco the postcode elephant 1986, Image The Postal Museum

There will be artwork and memorabilia from “Poco the Postcode Elephant”, a 1980s advertising campaign encouraging people to use their postcode.

Previously unseen maps of London from the 19th century will also be displayed and there will be the chance to check out your own postcode “profile”. It’s all come a very long way since the first postcodes trials in Norwich in 1959 and the full rollout, completed in 1974.

Today the postcode format comprises two main elements: the outward code (needed to sort from one town to another) and the inward code (required to sort within the town). And with an ever-changing landscape, the demand for new postcodes continues.

Poco’s Postcode Fan Club Membership Card 1980s; and, below, the back of the card. Images The Postal Museum

In the exhibition, visitors can try their hand at the Postcode Profiler interactive which offers “insight” into you via your postcode.

For the postcode has become a hugely powerful tool. Companies, charities and political parties for example use them to research potential customers, donors and supporters. Even pizza delivery companies use postcodes to determine which areas they will deliver to.

As for the Dollis Hill site, in 1968 it was announced that the Post Office Research Station would be moving to Suffolk. The site was released for housing. But a nearby road was named Flowers Close in honour of Tommy Flowers. In 1998, Flowers, who was married with two children, died aged 92.

King Edward Building, Sorting Office, EC district despatching 1928 © Royal Mail Group, courtesy of The Postal Museum

This exhibition will help shed light on him and many others and how the Post Office was one of the biggest and greatest innovators in mid-century Britain.

Chris Taft, head of collections at The Postal Museum says: “There was a great sense of national pride at the heart of the drive for innovation at the Post Office. The mechanisation of traditional systems, and ultimately the adoption of the postcode system, helped changed the face of Britain forever.”

• Sorting Britain: The Power of Postcodes runs from March 30 till January 1, 2023, at The Postal Museum,15-20, Phoenix Place, WC1X ODA. Details at postalmuseum.org