My history hero: Dame Stephanie Shirley chooses Tommy Flowers (1905–98)
The late tech pioneer and philanthropist Dame Stephanie Shirley, who died in August 2025 aged 91, chose Tommy Flowers as a history hero
In profile
Tommy Flowers was a British engineer with the Post Office. He’s best known for designing and building Colossus, the world’s first programmable electronic computer, which helped decrypt German messages during the Second World War. After the end of the conflict, Flowers continued to work for the Post Office, where he was involved in developing ERNIE, the random number generator used to pick Premium Bond winners.
When did you first hear about Flowers?
I had the privilege of working as a member of his team (on the first electronic telephone exchange, and later ERNIE) at the Post Office Research Station in Dollis Hill in the 1950s, when it was one of the leading research institutions in the world. However, he was a very senior figure in the organisation so my interaction with him was limited. I understood that he’d done something remarkable during the war, but the Official Secrets Act was taken very seriously in those days, and the story of Colossus didn’t really emerge until the 1970s.
What kind of man was he?
He was born in London’s East End, the son of a bricklayer and the grandson of a charlady. Growing up, money was tight and he was taught to be frugal. While doing an engineering apprenticeship, he took evening classes, gained a degree in electrical engineering and went on to have a distinguished career. I always found him polite, unassuming, and never sexist.
What made him a hero?
Because he changed the course of history, not once but twice. First, with his Colossus computer, which decrypted a huge number of high-level German messages during the Second World War, part of work estimated to have curtailed the conflict by up to two years. Second, with his pioneering work on early computers that paved the way for the modern digital world. He was also inspirational to me personally, as the sort of manager I wanted to become: he listened to his staff, got quality work out of them and attracted great loyalty. He was the nearest thing to a mentor to me.
What was his finest hour?
Designing and building the Colossus computer at Bletchley Park in 1943–44. The Mark I Colossus processed information five times faster than Bletchley’s previous code-breaking system. Tommy’s Mark II Colossus, which began operation on 1 June 1944, decrypted a German message confirming that Hitler, believing that preparations for landings in Normandy were a feint, wanted no extra troops sent there. That helped convince Eisenhower to go ahead with the D-Day landings on 6 June.
Can you see any parallels between his life and your own?
We both came from modest beginnings, and both studied part-time in the evenings to get our degrees at London University – his was in engineering, mine in mathematics.
What would you ask Flowers if you could meet him now?
I’d like to ask how he felt about the ridiculous lack of recognition he received in his lifetime. He was given an MBE and a couple of honorary doctorates, but that was pretty small fry. I don’t know how many people appreciate the true significance of his wartime work.
The late Dame Stephanie Shirley CH was a tech pioneer and philanthropist who came to Britain via the Kindertransport in 1939. Her memoir, Let It Go: My Extraordinary Story (Penguin), is available in paperback.
This article was first published in the September 2025 issue of BBC History Magazine
Authors
York Membery is a regular contributor to BBC History Magazine, the Daily Mail and Sunday Times among other publications. York, who lives in London, worked on the Mirror, Express and Times before turning freelance. He studied history at Cardiff University and the Institute of Historical Research, and has a History PhD from Maastricht University.