Sir Allen George Clark was an American born, British industrialist who helped to build the former Plessey company into one of Europe's largest manufacturers of telecommunications equipment, military electronics and aircraft components. His father was Byron George Clark, an American businessman who worked for United Shoe Machinery Corporation. In 1905 Clark was brought to England by his parents. Following his education at Felsted School, he joined the British Army and was wounded at Cambrai in 1917. He later joined the Royal Flying Corps and served in Egypt. In 1927 he became a British citizen. He joined the Plessey company in 1921 when his father bought a share of the company. Plessey was a small engineering company based in Ilford, Essex. Throughout the 1920s and 30s, Clark along with the engineer William Oscar Heyne, built Plessey into a large engineering company. During World War II, Plessey made an outstanding contribution to the nation's war effort producing munitions, aircraft components and electronic equipment. Clark remained in charge of the company throughout the war.
After the war Plessey continued to expand under the guidance of Clark, new products included industrial hydraulics, radar equipment, telecommunications equipment and semiconductors. In 1961 Plessey acquired the British Ericsson and AT&E companies, to become Britain's largest telecommunications equipment manufacturer.
He was awarded a Knighthood in 1961.He was Lord of the manor of Little Braxted.
He died from cancer in 1962; after his death, both of his sons, John Allen Clark and Michael William Clark continued to play an important role in the management of Plessey.
The Plessey Company purchased Braxted Park in 1947and the house was occupied by Sir Allen, chairman of the company and subsequently by his son, Michael Clark.