Walter was born in Kansas City, Missouri, United States, on 19 February 1910, the only child of Minerva Lucrezia (Margaret) Hardy (1879–1953), an American journalist and Karl Wilhelm Walter (1880–1965), a British journalist who was working on the Kansas City Star at the time.

He was brought to England in 1915, educated at Westminster School with an interest in classics and science, and entered King's College, Cambridge, in 1928.

According to his eldest son, Nicolas Walter, "he was politically on the left, a communist fellow-traveller before the Second World War and an anarchist sympathiser after it.

As a young man, Walter was greatly influenced by the work of the Russian physiologist Ivan Pavlov.

[citation needed] He visited the lab of Hans Berger, who invented the electroencephalograph, or EEG machine, for measuring electrical activity in the brain.

He developed the first brain topography machine based on EEG, using an array of spiral-scan CRTs connected to high-gain amplifiers.

[7] Intriguingly, this effect brings into question the very notion of consciousness or free will, and should be considered as part of a person's overall reaction time to events.

His first robots, which he used to call Machina speculatrix[10] and named Elmer and Elsie, were constructed between 1948 and 1949 and were often described as tortoises[11] due to their shape and slow rate of movement - and because they "taught us" about the secrets of organisation and life.

The three-wheeled tortoise robots were capable of phototaxis, by which they could find their way to a recharging station when they ran low on battery power.

His work inspired subsequent generations of robotics researchers, including Rodney Brooks, Hans Moravec and Mark Tilden.

[1] After the couple separated in 1945, and divorced in 1946, their children were brought up by their mother Monica and her second husband Cambridge University scientist Arnold Beck.