The Plessey Company plc was a British-based international electronics, defence and telecommunications company. It originated in 1917, growing and diversifying into electronics. It expanded after the second world war by acquisition of companies and formed overseas companies. In 1989 it was taken over by a consortium formed by GEC and Siemens which broke up the Plessey group. Only a few organisations now remain with the Plessey name.
The manufacture of electrical components also became a key area of growth for Plessey, a vast array of different components was manufactured by the company, 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.
To allow greater production, Plessey converted 5 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, and opened several other shadow factories around the country producing munitions. Caswell became the first dedicated research centre in 1940. The wartime workforce of Plessey grew to over 10,000 people.
In 1951 the Electronics Division was started by Michael Clark. By 1955 this had expanded to become the Electronics and Equipment Group with 5000 staff. The following year the Roke Manor Research Limited facility was set up under the direction of H.J. Finden. In the 1960s the Group continued to expand, setting up facilities at places such as West Leigh and Templecombe.
In 1961 Plessey merged with the British Ericsson Telephone Company, and the Automatic Telephone & Electric (AT&E), 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 1970 the Command and Control unit was set up at Christchurch, which became the centre of the Plessey Defence Systems business. In 1979 a major subsidiary was set up, Plessey Electronic Systems Ltd, which incorporated the three businesses and achieved sales of over £500 million and employed 15000 people by 1986.
Plessey were partners in the development of the Atlas Computer in 1962 and in the development of Digital telephone systems—System X—during the late 1970s. The Plessey 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.
During the 1970s and early 1980s, Plessey manufactured a series of computer systems and peripherals compatible with Digital Equipment Corporation's PDP-11. 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 that adopted the Plessey System 250 architecture.
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 300 x 150 feet and filled with around 1000 seven foot high 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 60s. During this period the company effectively became the world leader in computer design... unfortunately this fact remained a close secret.
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.
At the time, IMC was in the process of industrialising a unique South African invention, the Tellurometer, the first successful microwave electronic distance measurement equipment (EDM). The Tellurometer was invented by Dr. Trevor Lloyd Wadley of the Telecommunications Research Laboratory of the South African Council for Scientific and Industrial Research (CSIR), also responsible for the Wadley Loop receiver, which allowed precision tuning over wide bands, a task that had previously required switching out multiple crystals. The Wadley Loop was first used in the Racal RA-17 a 1950s top of the range British military short wave receiver still considered one of the finest radio receivers ever made and later in the South African made commercially available "Barlow-Wadley XCR-30" radio.
The Tellurometer design yielded high accuracy distance measurements over geodetic distances, but it was also useful for second order survey work, especially in areas where the terrain was rough and/or the temperatures extreme. The original Tellurometer, known as the Micro-Distancer M/RA 1, used a continuous wave at 3,000 megahertz, modulated by 10 megahertz and three other nearby frequencies. The remote station reradiated the incoming wave in a similar wave of more complex modulation, and the resulting phase shift was a measure of the distance travelled. The results appeared on a cathode ray tube with circular sweep. This instrument could penetrate haze and mist in daylight or darkness, and had a normal range of 30-50 km. It was covered by patents in at least eleven countries granted to Wadley and assigned to the CSIR. Under the Plessey mantle, Tellurometer (Pty) Limited was formed, which proceeded to manufacture the product and to develop and sell derivatives for decades to come. The subsequent years saw the introduction of numerical displays, solid state transmitters, integrated circuits and eventually microprocessors, all of these being adopted and mastered by a vibrant development team. A wide range of point to point microwave EDMs was produced, including the MRA7, which could measure distance up to 50 km with an accuracy of 15 cm, is still produced in limited numbers today. The product range included a 100km position fixing system, with fixed remote stations and a ship borne master station as well as three optical EDMs, the last of which was able to measure up to 1 km with an accuracy of 0.6 mm.
South African insurance and investment company Sanlam bought 26% of Plessey South Africa in 1974 with first right of refusal to purchase more of the company. These shares were later transferred to Sankorp, Sanlam’s industrial holdings company. Fifteen years later, in 1989, GEC-Siemens took control of the Plessey Company plc and Sankorp indicated its intention to purchase the remaining 74% of shares in the South African subsidiary.
GEC Plessey Semiconductors (GPS) was purchased by Mitel Semiconductors of Canada in 1998. After a number of downsizes, including the power semiconductor and silicon on sapphire operation at Lincoln, Lincolnshire being purchased in January 2000 by Dynex Semiconductor, the company renamed itself Zarlink Semiconductor in 2001. The GPS fab in Plymouth was acquired by Xfab and still houses a small Zarlink test facility.
In South Africa, following the successful GEC/Siemens takeover, after protracted negotiations, in 1991 Plessey South Africa became a wholly owned subsidiary of Sankorp under the new name of Plessey Tellumat South Africa Limited (PTSA). The addition of the name Tellumat had a double symbolism, firstly for the company's commitment to exports, as it is the name of its UK-based export subsidiary. Secondly the name derives from the Tellurometer South Africa's world first electronic surveying development—and by implication a commitment to ongoing electronic research and development.
Plessey Tellumat continued to grow, with a strong focus on telecommunications and defence products and solutions and particularly with a major expansion into large projects, rolling out the microwave backbone of MTN, one of South Africa’s first GSM cellular networks and the installation of a fibre optic network and radio broadcasting system in Malaysia. A software division was formed through the acquisition of BSW data, largely staffed by engineers from the recently-terminated South African space programme, in which Plessey had also participated, both in the electronics of the launch vehicle and the satellite itself.
1995 was a landmark year in the history of Plessey in South Africa. The merger of PTSA and Tek Electronics, the consumer electronics audio and video products, manufacturer and distributor, (also wholly-owned by Sankorp) took Plessey full circle back to its consumer electronics roots. This resulted in the renaming of PTSA back to the original name of Plessey South Africa Limited. The acquisition of Amalgamated Wireless Australia (AWA) which had a similar product portfolio, resulted in penetration into the Pacific Rim market. The culmination of this growth was the company’s listing on the Johannesburg Stock Exchange (JSE) as the Plessey Corporation in the same year. Trading started off at R4.80 a share. On the evening of the 6th of February 1996, a devastating fire swept through 2 bays of the White Road factory in Retreat, Cape Town causing huge damage to stock, instruments, plant and work in progress. No one was injured, but work was disrupted for several weeks. Large sections of the factory had to be rebuilt.
At the end of 1996, Plessey sold off the Sales and marketing business of Telefunken, Pioneer and Satellite TV. The manufacturing facility in East London was retained.
In August 1998 Plessey was bought by Dimension Data Holdings and World-wide African Investment Holdings for R1.6 Billion. The new owners retained BSW Data, Plessey Solutions and Communications Systems. The remaining divisions, notably with a product development and manufacturing focus, were bought back by a combined management buyout supported by Rand Merchant Bank. The corporate name was changed to Tellumat Pty Ltd ([www.tellumat.com]).
Tellumat continues to develop and manufacture Plessey-branded products as before and operates in the Defence, Telecommunications and Contract Manufacturing Markets.
Plessey barcodes use two bar widths. Whitespace between bars is not significant. The start element is a wide bar, and the stop element is two narrow bars. In between, the bars are in groups of four. High order bars appear leftmost. Narrow bars are zero and wide bars are 1.
This symbology is not self checking, though a modulo 10 or modulo 11 checksum (depending on application) is usually appended.