Colossus machines - the world's first electronic, digital computers - had a single purpose: to help decipher the Lorenz-encrypted messages between Hitler and his generals during World War II. The information gleaned from the decrypted messages is widely acknowledged to have shortened the war by many months, saving tens of thousands of lives.

Colossus machines were in operation at Bletchley Park from early February 1944, although the building in which the earliest Colossi were housed, F Block, has since been demolished. Out of a total of 10 machines, six Colossi (Nos 5 - 10) were in operation in Block H at Bletchley Park during WW2.

Colossus was preceded by several computers, many of them being a first in some category. Colossus, however, was the first that was digital and electronic. The first fully programmable digital electronic computer capable of running a stored program was still some way off in the form of the Manchester Small Scale Experimental Machine (1948).

The use to which the Colossi were put was of the highest secrecy, and Colossus itself was highly secret, and remained so for many years after the War. Colossus was not included in the history of computing hardware for decades, and Flowers and the GPO engineers who worked alongside him were deprived of the recognition they were due for many years.

In this online lecture, TNMOC volunteer Peter Hoath will explain about the origins of Colossus, and the brilliant minds that brought it into existence. Hosted as part of Buckinghamshire History Festival.