Ten British computers that changed the world

The world’s oldest working digital computer has been brought back to life at Bletchley Park, Buckinghamshire. (Image: Wikimedia)
Julian Gavaghan

Atlas, commemorated this week at Manchester University, was the most powerful computer in the world in 1962 - but it wasn't the only British computer that changed the world.

The UK has been at the forefront of this technological revolution. Here are ten other British computers that changed the world.

Difference Engine

Although never completed, Charles Babbage created the world’s first design for a computer in 1822 in a bid to remove error from mathematics.

His 15-ton mechanical machine, which was only constructed 169 years later, used giant valves to calculate times tables.

In its first calculation in 1991 it returned results up to 31 digits, which is more than most modern pocket calculator can.

The Bombe

The Bombe was a groundbreaking 1939 electro-mechanic computer that helped the Allies win World War II by cracking the daily settings of the Germans’ Enigma Code.

Designer Alan Turing (pictured) first helped developed the algorithm to decipher the differently encrypted messages at Bletchley Park.

Then the Bombe went to work to reveal the Enigma Machine’s settings each day.


The first programmable electronic digital computer was also built at Bletchley Park in 1943.

It deciphered the Lorenz code, which was used by senior German commanders, including Adolf Hitler.

Sadly, neither Colossus nor its creator, Tommy Flowers, were recognised by the world for decades due to the Official Secrets Act.


The Manchester Small-Scale Experimental Machine, nicknamed Baby, was first operated in 1948 and was the world’s first stored-programme computer.

It had a 32-bit memory and, although limited in what it could do, became the protpotype for all modern, general-purpose computers.

It was the first to demonstrate random access  memory by calculating complicated mathmatical sums – taking almost an hour to do so.


The Electronic Delay Storage Automatic Calculator was built by Maurice Wilkes and his team at Cambridge University in 1949.

It was the second stored-programme computer and was seen as a real leap forward.

But perhaps its real significance was helped team member David Wheeler earn the world’s first Computer Science PhD in 1951.


In typical British eccentricity, the world’s first computer used by a business was developed by a chain of tea shops in 1951.

Refusing to focus on just tea, Lions built the Lions Electronic Office, or LEO.

The card-reading computer, which had an 8.75kbyte memory, was used to calculate inventory, production requirements and organise payroll.


Ferranti Mark 1

The Ferranti was the world’s first general purpose commercial computer.

The machine, which was built in Oldham in 1951 and based upon Manchester University’s Baby, helped developed a new purpose for information technology.

It stores the earliest recording of music on a computer (God Save The King and Baa Baa Black Sheep) and one of the first video games (chess).

Manchester Transistor Computer

This was the first digital computer that wasn’t operated by vacuum tubes.

Instead the machine, designed by the University of Manchester in 1953, used revolutionary transistors, which switch electric signals and were potentially faster.

The Transistor Computer could calculate complicated sums, although it would usually overheat after 90 minutes.

Sumlock ANITA calculator

The ANITA Mark VII, built by the Bell Punch Company in west London, was the world’s first fully-electronic desktop calculator.

Costing £400 – or around £7,300 in today’s money – it was around the same size as a modern laptop.

It was revolutionary because it was actually relatively affordable. Electronic computers then cost about £50,000.


ICL 2900 Series

In a bid to keep up with major global competitors, the British government encouraged the merger of the last two big British firms to form International Computers Limited.

Its most successful product was the ICL 2900 series of mainframes launched in 1974.

It was a big step in the evolution of efficient operating system.

However, ICL relied on government contracts and was ultimately bought by Fujitsu in 2002.