Login »

How one man's vision opened the door to today's communications systems — from operators manually routing calls, to the fibre networks being laid today.

In 1947, while on holiday in Barmouth, Tommy Flowers — already known for building Colossus at Bletchley Park — started thinking about how a computer could be used to route telephone calls. He set up a team at the GPO Research Station at Dollis Hill to chase down ideas that were groundbreaking at the time and are commonplace now.

Under our feet and above our heads, a quiet revolution is happening: a century of copper cable is being replaced by fibre optic. For the first time in over a hundred years, the technology connecting every one of us is being upgraded. Flowers to Fibre tells that story, from the Strowger years through to fibre optics feeding in beyond 2025.

Panoramic view of the Flowers to Fibre exhibition space, from the fibre last-mile display to the exhibition entrance
Inside the exhibition — from the fibre last-mile display and red kiosk door on the left, through to the entrance on the right.

What's on display

  • The Strowger years and early electromagnetic telephone exchange technology
  • Tommy Flowers' work laying the foundations for fully electronic exchanges
  • The Highgate Experiment and the eventual breakthrough with Empress and Moorgate
  • The System X revolution that brought digital switching to the telephone
  • Before "always on" — the story of dial-up networking
  • The dawn of broadband, and fibre optics feeding in beyond 2025

Featuring an interactive, working Strowger telephone exchange, an original System X prototype, and a working dial-up service for PC internet access. There's also an interactive digital quiz, plus STEM activities and competitions for children and schools.

Tommy Flowers MBE, 1905–1998

Portrait of Tommy Flowers MBE

Designer of the Colossus electronic computer, and lead researcher at GPO Telecommunications Research into electronic switching.

A film made by researchers at Dollis Hill in the early 1970s, showing what they envisioned communications would be like by the 1990s.

In the exhibition

01

Place a real call through history

A hands-on exchange demonstration lets visitors dial out on a black Bakelite Strowger-dial phone, a classic red 746, and a 1970s push-button set — each routed through a working rack of real exchange equipment.

Interactive phone demonstration table with black, red and yellow telephones connected to exchange equipment
02

Tommy Flowers: the boy from Poplar

A full biography panel traces Flowers from his 1905 birth in Poplar and 1921 apprenticeship at Woolwich Arsenal, through his 1930 transfer to the GPO's Dollis Hill research station, his 1943 work on Colossus at Bletchley Park, and his 1947 return to lead the GPO's digital exchange research.

Panels on the System X revolution and Tommy Flowers' biography, with Dollis Hill research station history
03

The Highgate Experiment

In 1962 the world's first solid-state phone exchange took its first calls at Highgate, London — a converted Strowger exchange housing 3,000 valves, 26,000 transistors and 350,000 other components, with results engineers themselves described as mixed.

The Highgate Experiment display panel with exchange equipment on show
04

Breakthrough with Empress and Moorgate

In 1968 the Empress exchange in Kensington became the world's first phone exchange to switch calls digitally, using Pulse Code Modulation — a technique invented decades earlier by Alec Reeves but only made practical once transistors replaced valves.

Breakthrough with Empress and Moorgate display panel, with Alec Reeves and Pulse Code Modulation history
05

A System X prototype

A rare surviving prototype concentrator from System X, the digital switching system that became Britain's standard exchange technology through the 1980s and 90s, sold by Plessey, GEC and Telecom.

System X prototype concentrator rack on display
06

Dial-up internet, the way you remember it

A working 1990s PC and modem lets visitors dial up and browse the early web at authentic dial-up speed — and hang up properly afterwards, the way everyone had to before "always on" broadband existed.

1990s PC and modem set up for a dial-up internet demonstration
07

Fibre and the last mile

A recreated telegraph pole and green street cabinet show exactly how fibre gets from the exchange to your door today — right down to the network termination equipment that would be fixed to a real building. A single fibre line card, using Gigabit Passive Optical Network technology, can serve up to 2,048 customers.

Recreated telegraph pole and green cabinet showing fibre last-mile connection equipment Close-up of a fibre line card, capable of serving up to 2048 customers using GPON technology

The exhibition in action

A visitor placing a call on the historic telephone demonstration Visitors examining the Highgate exchange rack Visitors examining the fibre last-mile telegraph pole display

Sponsored by

Andrews & Arnold — for home, business, or home office, A&A delivers high quality internet connectivity and VoIP. They aim for low latency and no "evening slowdown" through their own network capacity and monitoring, with UK-based staff who know the subject rather than read from a script.

Plan your visit

Where

Block H, The National Museum of Computing, Bletchley Park, Milton Keynes MK3 6EB

Tickets

CMT Members get admission discount,show your membership card at the door.

Help us keep it working

Exhibitions like this run on volunteer time and support from people who care about it.

Support us