Plessey father and sons

 Allen Clark, son of Byron Clark, was born in Massachusetts in 1898 and came to England in 1905. He attended Felsted School. In the First World War he served in the London Scottish and was wounded at Cambrai in 1917. He then joined the Royal Flying Corps.

in 1920, Byron Clark bought Plessey Limited which made tools in Marylebone in London. In 1922 Plessey obtained a contract to made crystal radio sets for Marconi and I write of this in How Britain Shaped the Manufacturing World. Marconi invested in Plessey, secured seats on the board and Plessey developed a business in making radio components.

Allen is remembered by his friend Patrick Hennesey, one time boss of Ford UK, as a man dedicated to searching the world for ideas which could enable Plessey to develop.

Plessey became a public company in 1937 and I write in HBSTMW of its contribution to the national effort in the Second World War. After the war, Allen was joined by his sons John and Michael.

John was educated at Harrow and Cambridge and served in the RNVR from 1944 to 1947. He then went to learn about electronics manufacturing first at Metro-Vick and then in the USA before joining Plessey.

John had a particular interest in materials such as gallium arsenide and silicon and took on the development of the semiconductor business and master minded Plessey's research into materials at its Caswell laboratories. A plant for manufacturing pure silicon was established in 1952 but the potential for solid state technology had yet to be embraced. It wasn't until 1957 that the company began manufacture of transistors. 1966 MOS integrated circuits were produced at Swindon, making Plessey the first European manufacturer of such microcircuits.

In 1951 a Communications Division was formed, with Michael Clark at its head, and a remit to catch up with its competitors in VHF and UHF equipment. Two senior managers, John Cunningham and Raymond Brown, left Plessey to form Racal.

Allen's big break came in 1961 when Plessey took over competing telephone manufacturers Ericsson Telephone Ltd and the Automatic Telephone and Electric Company. He was knighted that same year but tragically died before the transaction completed. He was succeeded by John as chairman and Michael as managing director.

In 1965 the company reorganised into five product groups: Automation, Components, Dynamics, Electronics, Telecommunications. The company went on to develop their electronics business in defence, semiconductors and computers. I write of all of this in Vehicles to Vaccines. In 1962, Plessey had 25,000 employers and this grew to 75,000 by 1980 in a number of different locations with head office at Ilford as I wrote in How Manufacturing Shaped Britain.

GEC and Plessey merged their telecoms businesses in GPT in 1988 and in 1989 Siemens and GEC purchased the remainder of Plessey. John Clark was knighted in 1971 and died in 2001. Michael was awarded a CBE and survived his brother by nine years.

Further reading:

Richie, Berry, Into the Sunrise - Plessey Company (London: James & James, 1989)