Plessey
The Plessey Company plc was a British electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after World War II by acquisition of companies and formed overseas companies. It was listed on the London Stock Exchange and was a constituent of the FTSE 100 Index. In 1989, it was taken over by a consortium formed by GEC and Siemens which split the assets of the Plessey group.
The majority of Plessey's defence assets were amalgamated into BAE Systems in 1999 when British Aerospace merged with the defence arm of GEC, Marconi Electronic Systems. The Plessey Microsystems division was the subject of a management buyout in 1988 becoming Radstone Technology, which survives today as part of Abaco Systems based in Towcester, Northamptonshire. The bulk of Plessey's telecommunications assets were acquired by Ericsson through its 2005 acquisition of Marconi Communications, a successor company of GEC.
History
Early history
The Plessey company was founded in 1917 in Marylebone, central London. The original shareholders were Thomas Hurst Hodgson, C. H. Whitaker, Raymond Parker and his brother Plessey Parker. A talented German engineer, William Oscar Heyne, was employed by the company. Heyne later became the managing director and chairman of Plessey and was one of the key figures in the development of Plessey during the 1920s and 1930s. The company moved to Cottenham Road in Ilford early in 1919. In 1925, the original company was wound up and a new one was formed with a greater share capital. Most of the early work carried out by the company was in mechanical engineering.The Clark connection
An early customer of Plessey was a galvanising company called British Electro Chemists. One of that company's shareholders was Byron G. Clark, an American, who was also a business associate of T. H. Hodgson, one of the founders of Plessey. The Clark family would eventually dominate the management of Plessey for most of its history. Byron's son Allen George Clark joined the company in 1921, and went on to become a driving force behind the development of Plessey, followed later by his sons John Allen Clark, and Michael William Clark, both of whom rose to prominent positions in the company.Electrical manufacturing
During the 1920s Plessey began to diversify into electrical manufacturing. Important contracts included the manufacture of early radios for Marconi and the production of telephones for the General Post Office. In order to increase production, Plessey moved to Vicarage Lane, Ilford, in 1923. In 1929, the television pioneer John Logie Baird had his first production televisions made by Plessey. The company also produced the first British-made portable radio in the same year.The manufacture of electrical components became an area of growth for Plessey. A vast array of components was manufactured, many under licence from overseas companies. Plessey became one of the largest manufacturers in this field as the radio and television industries grew. In 1936/7, turnover was more than £1 million and Plessey became a public company on 17 March 1937.
Aircraft components
Aircraft components was another market into which the company diversified. In 1936, Plessey obtained a number of important manufacturing licences from American companies such as Breeze Corporation for aircraft multi-pin electrical connectors, Federal Laboratories for Coffman starters, and Pump Engineering Services Corporation for the manufacture of Pesco fuel pumps. Plessey went on to produce large numbers of these fuel pumps for Rolls-Royce Merlin engines, and in 1940 the fuel pump for Britain's first jet engine was also supplied by Plessey.Image:R1155 Receiver and T1154 Transmitter at RAF Digby.jpg|thumb|upright|R1155 receiver on top of T1154 transmitter
World War II
During World War II, Plessey produced a vast array of components and equipment for the war effort, including shell cases, aircraft parts, and radio equipment such as the R1155, and T1154. In all, 161,500 pieces of wartime electronic equipment were produced.To allow greater production, Plessey converted five miles of twin tunnel, built for a new extension to the London Underground Central line from Leytonstone to Newbury Park, into a factory. The company also built a new factory at Swindon in Wiltshire, and opened several other shadow factories around the country to produce munitions. Caswell, Northamptonshire became the site of Plessey's first dedicated research centre in 1940. The wartime workforce of Plessey grew to over 10,000.
Post World War II
With the end of the war the company's orders dropped from £5 million in 1944/5 to £263,000 in 1946 and the workforce fell to less than 6,000. Radio and television sales were the main area of activity until the renewed demand for defence products with the onset of the Korean War. From a turnover of £5 million in 1949/50, there was an increase to £32 million in 1959/60.In 1951, the Electronics Division was started by Michael Clark. By 1955, this had expanded to become the Electronics and Equipment Group with 5,000 staff. The following year the Roke Manor research facility was set up under the direction of H. J. Finden near Romsey, Hampshire. Plessey produced an early integrated circuit model in 1957, before the patents of Jack St. Clair Kilby of Texas Instruments and Robert Noyce of Fairchild. In the 1960s the Group continued to expand, setting up facilities at places such as West Leigh and Templecombe, Somerset.
Image:Plessey.png|thumb|Plessey Electronics logo
In 1961 Plessey merged with Ericsson Telephones and Automatic Telephone Manufacturing Company of Liverpool, to become Britain's largest manufacturer of telecommunications equipment, including the majority of the country's crossbar switches. Alongside the Telecommunications Division, three other businesses were set up: Plessey Avionics and Communications, Plessey Radar and Plessey Marine. In 1967 or 1968, English Electric was subject to a takeover bid by Plessey, but chose instead to accept an offer from GEC. In 1970, the Command and Control unit was set up at Christchurch, Dorset, which became the centre of the Plessey Defence Systems business. In 1979, a major subsidiary was set up, Plessey Electronic Systems, which incorporated the three businesses and by 1986 achieved sales of over £500 million and employed 15,000.
Plessey were partners in the development of the Atlas Computer in 1962 and in the development of digital telephone systems, including System X, from the late 1970s. In 1988, Plessey's Telecommunications Division merged with that of GEC to become GEC Plessey Telecommunications. Plessey Naval Systems was formed in 1986 by the merger of Plessey Marine with Plessey Displays, which had been part of Plessey Radar. Plessey were among the first firms to use computers. Their Training Department developed an interactive management game using TeleType printer/keyboards to link to LEASCO computers in the United States via standard telephones and acoustic couplers.
Plessey also pioneered the gathering and consolidation of accounting information from around the world using in-house software. Each of their 140 management reporting entities used HP125s with DIVAT software. Nearly 450 validation rules ensured accuracy within and between various reports. The data were then transmitted to Ilford where a HP 3000 ran Fortran software for consolidation and reporting—also on HP125s. By 1972, Plessey designed the first industrial capability-based security computer, a fault-tolerant multiprocessor system called Plessey System 250. Plessey was also the lead contractor for the Ptarmigan communications system supplied to the British Army, which adopted the System 250 architecture.
A division focused on microcomputing, Plessey Microsystems, was founded in 1975, having licensed the 16-bit Miproc processor architecture developed by the Norwegian Defence Research Establishment and Aksjeselskapet Mikro-Elektronikk. In contrast to the existing implementation, announced with a 200ns cycle time, Plessey introduced Miproc with a 350ns cycle time as part of a development system costing $. During the 1970s and early 1980s, Plessey manufactured a series of computer systems and peripherals compatible with Digital Equipment Corporation's PDP-11, some based on the Miproc product which was itself revised to operate with a faster 250ns cycle time. The company would eventually expand its Miproc range to include the Miproc RTS, running the RTX real-time operating system, alongside Plessey's other product lines featuring semiconductor and bubble memory, and microprocessor-based data terminals.
Plessey Controls, from 1982 to the mid-1980s, also manufactured a type of geiger counter known as the Portable Dose Rate Meter. It gave highly accurate readings, using the Gray system of measurement and used standard torch batteries. They were built for civil defence, but also used by the British Army. Most ended up in the hands of the Royal Observer Corps and manufacture would discontinue by the late 1980s.
UK air defence
In 1959 AT&E, later Plessey, became the prime contractor for a new UK air defence system, known by the company under the name Plan Ahead and, from 1961, as Project Linesman. To enable the system to be designed and built without too much information becoming public knowledge, a new factory called "Exchange Works" was built in Cheapside in Liverpool city centre, where young employees were granted exemption from conscription.At the heart of the system, installed in a huge building in the middle of a council housing estate in West Drayton, was the computer room, occupying an area of around and filled with around 1,000 racks of electronics, including mainly the XL4 computer, based entirely on germanium transistors and using a computer language developed at Exchange Works in the 1950s and 1960s. The secure status of the factory attracted many other secret contracts and led to it becoming one of the major designers and manufacturers of cryptographic equipment. Exchange Works is now luxury flats.