Industry Electronics, defence and telecommunications
Fate Acquired
(in 1989 by GEC/Siemens joint holding company - GEC Siemens plc)
Successor GEC
(1989 - 1999)
Siemens Plessey
(1989 - 1997)
Marconi Communications
(1998 - 2006)
Siemens Communications
(1998 - 2006)
BAE Systems
(1999 till date)
Founded 1917
Defunct 1989
Headquarters Ilford, England
Key people
Sir John Clark (Chairman)

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.

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 BAe merged with the defence arm of GEC, Marconi Electronic Systems (MES). A small portion of the defence market, mostly embedded electronic systems and circuitcards remained with GE, formerly GE Fanuc and now GE Intelligent Platforms (GE-IP) based out of Towcester. The bulk of Plessey's telecommunications assets were acquired by Ericsson through its 2005 acquisition of Marconi Corporation plc, a successor company of GEC. The remainder of the communication assets went to Telent plc.


  • History 1
    • Early history 1.1
    • The Clark connection 1.2
    • Electrical manufacturing 1.3
    • Aircraft components 1.4
    • Second World War 1.5
    • Post World War II 1.6
    • UK Air Defence 1.7
    • Plessey in South Africa 1.8
    • GEC takeover bid 1.9
    • GEC Siemens takeover 1.10
  • Break-up of the business 2
    • GEC acquisitions 2.1
    • Siemens acquisitions 2.2
    • Jointly owned 2.3
    • Disposals 2.4
  • Subsequent history 3
    • UK 3.1
    • Plessey Semiconductors Ltd. 3.2
    • South Africa 3.3
  • Plessey barcodes 4
  • References 5
  • External links 6


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.[1] 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 30s.[1] The company moved to Cottenham Road in Ilford early in 1919 (and then to Vicarage Lane where it remained).[1] In 1925 the original company was wound up and a new one formed with a greater share capital. Most of the early work carried out by the company was mechanical engineering rather than electronics.

The Clark connection

An early customer of Plessey was a

  • History of Plessey
  • Plessey history

External links

  1. ^ a b c d e f g h i j k l m n o p "A résumé of the history of Plessey, compiled by Hugh Culverhouse, a nephew of Sir Allen Clark". Retrieved 4 April 2012. 
  2. ^ "Michael Clark". The Daily Telegraph (London). 10 August 2010. 
  3. ^ Peter Robin Morris, Institution of Electrical Engineers "A history of the world semiconductor industry"
  4. ^ 50th anniversary of the IC
  5. ^ a b 40 years of Marconi Radar 1946 to 1986
  6. ^ Tellurometer MRA 1
  7. ^ Plessey SA: Timeline
  8. ^ a b c The Integration of Acquired Companies Into the Defence Industry: Experiences. Retrieved 16 July 2012.  by Karin Backlund, Madelene Sandstro
  9. ^ a b c "‘The DECCA Legacy’ A view from inside the RADAR company -DECCA - BAE SYSTEMS (1949 - 2009)". Retrieved 16 July 2012. 
  10. ^ IPD Group: GEC History
  11. ^ "The Plessey Carve-up". Financial Times (The Financial Times Limited). 1990-04-04. p. 26. 
  12. ^ Birkbys
  13. ^ British Aerospace buys Siemens
  14. ^ GEC buys Siemens out of GPT
  15. ^ Marconi Communications
  16. ^ Mitel buys GEC Plessey
  17. ^ Janes: Zarlink Semiconductors
  18. ^ Press release from X-FAB 1 December 2009, accessed 9 April 2012X-FAB und Plus Semi vereinbaren Verkauf von X-FAB UK (German)
  19. ^ Linkedin page of Plus Semi, accessed 9 April 2012
  20. ^ Tellumat: Introduction


This symbology is not self checking, though a modulo 10 or modulo 11 checksum (or some combination of both checksums, depending on application) is usually appended.

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.

The name is also used to refer to a barcode symbology developed by Plessey, which is still used in some libraries and for shelf tags in retail stores, in part as a solution to their internal requirement for stock control. The system was first used in the early 1970s by J.Sainsbury to identify all of its products on supermarket shelves for its product restocking system. The chief advantages are the relative ease of printing using the dot-matrix printers popular at the time of the code's introduction, and its somewhat higher density than the more common 2 of 5 and 3 of 9 codes.

"123456E" encoded in a Plessey barcode

Plessey barcodes

In August 1998 Plessey Corporation 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.[20] Tellumat continues to develop and manufacture Plessey-branded products as before and operates in the Defence, Telecommunications and Contract Manufacturing markets.

At the end of 1996, Plessey Corporation sold off the Sales and marketing business of Telefunken, Pioneer and Satellite TV.[1]

1995 was a landmark year in the history of the business 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 the business full circle back to its consumer electronics roots.[1] This resulted in the renaming of PTSA back to the original name of Plessey South Africa Limited. The full acquisition of AWA-Plessey Communications, which Plessey jointly owned in Australia with Amalgamated Wireless (Australasia) Ltd (AWA) and 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.[1] On the evening of the 6th of February 1996, a devastating fire swept through two 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.[1]

PTSA 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 PTSA had also participated, both in the electronics of the launch vehicle and the satellite itself.

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.

South Africa

The Roborough site ( 8" and 6" lines) was re-acquired from Xfab on the 1 January 2010 and the company renamed as Plessey Semiconductors Ltd. The new company transferred its Bipolar processes on Silicon & SOI into the 8” Plymouth facility during 2010, exploiting the combined technology base in the development of new processes and products in a number of markets. Specifically, it is focused on military, medical, aerospace, space and automotive markets. The Swindon site on the Cheney Manor Industrial estate in the west of the town was finally demolished in July 2012.

After the sale of the Roborough site in Plymouth to Xfab, the original Plessey Semiconductors site at Cheney Manor, Swindon continued to operate under the Zarlink Semiconductor name until it was sold to MHS Industries in early 2008. In February 2009 the UK business was forced into receivership following the collapse of the parent MHS Electronics business in France. After a subsequent management buyout the company traded as Plus-Semi Ltd.[18][19]

Plessey Semiconductors factory at Cheney Manor, Swindon on 17 July 2012, undergoing demolition
Plessey Semiconductors factory at Cheney Manor, Swindon in 1982. The factory housed both bipolar and MOS lines. A small part of the canteen facilities (which had five grades of service) for all Plessey employees is visible on the right of the image, since demolished around 2010

Plessey Semiconductors Ltd.

GEC Plessey Semiconductors (GPS) was purchased by Mitel Semiconductors of Canada in 1998.[16] 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.[17] The GPS fabrication plant in Plymouth was acquired by Xfab and still houses a small Zarlink test facility.

The part of GPT which evolved into Siemens Communications, would eventually evolve into Siemens Enterprise Communications in 2008. The GEC acquired part of GPT (August 1998) which became Marconi Communications in 1999, would be amalgamated into both Ericisson and Telent in 2005 when they acquire its parent company - Marconi Corporation plc, formed by 2003 restructuring of Marconi plc.[15]

By 1997 GPT name disappeared in UK, and the company was known by Siemens GEC Communication Systems (SGCS), which later became 'Siemens Communications'. In August 1998 GEC acquired Siemens' 40% stake in GPT (by now only exist as a legal entity); and merged GPT with the telecoms units of its other subsidiaries namely - Marconi SpA, GEC Hong Kong and ATC South Africa to form Marconi Communications. In December 1999, GEC's defence arm - 'Marconi Electronic Systems' was amalgamated with 'British Aerospace' to form 'BAE Systems'. The entity left out of 'GEC' was renamed to Marconi plc, and Marconi Communications became its principal subsidiary.[14]

In 1997 British Aerospace and Daimler-Benz Aerospace acquired the UK operations and German part of Siemens Plessey Systems, respectively.[13]


Subsequent history

  • Birkby Plastics[12]
  • Hoskyns Group
  • Plessey Spa (Italy)
  • 51% share in Plessey Telenet acquired by minority partner in 1992.
  • 74% share in Plessey South Africa


  • GEC-Plessey Telecommunications (GPT): 60% GEC and 40% Siemens

Jointly owned

  • Siemens Plessey Radar
  • Siemens Plessey Defence Systems
  • Siemens Plessey Controls
  • Siemens Plessey Australia
  • Siemens Plessey Assessment Services
  • Roke Manor Research Limited

Siemens acquisitions

  • UK
    • Plessey Aerospace
    • Plessey Avionics
    • Plessey Crypto
    • Plessey Materials
    • Plessey Naval Systems
    • Plessey Semiconductors
    • Plessey Research Caswell
  • North America
    • Plessey Aero Precision Corp
    • Plessey Dynamics Corp
    • Plessey Electronic Systems Corp (including ES Marine Systems)
    • Sippican Inc
    • Plessey Materials Inc
    • Leigh Instruments

GEC acquisitions

In April 1990 GEC and Siemens agreed a new structure of ownership of the Plessey businesses:[8][9][11]

Break-up of the business

[10][9][8] In 1988 GEC and

GEC Siemens takeover

In 1988 Plessey and The General Electric Company (GEC) merged their telecom units to form GEC-Plessey Telecommunications (GPT), the UK's leading telecommunications manufacturer.

In December 1985 GEC launched a takeover bid for the Plessey Company, valuing the group at £1.2 billion. Both Plessey and the Ministry of Defence were against the merger, GEC and Plessey were the two largest suppliers to the MoD and in many tenders the only competitors. In January 1986 the bid was referred to the Monopolies and Mergers Commission (MMC), whose report published in August advised against the merger. The government concurred and blocked GEC's bid.[8][9]

GEC takeover bid

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.[7] 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.

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).[6] 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 South African roots of Plessey can be traced to the acquisition of AT&E and Ericsson in 1963 and a Cape Town-based company, the Instrument Manufacturing Company (IMC), acquired in 1964.[1]

Plessey in South Africa

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.

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 by 150 feet (91 m × 46 m) and filled with around 1,000 7-foot-high (2.1 m) 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.[5] During this period the company effectively became the world leader in computer design... unfortunately, this fact remained a close secret.

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.[5] 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.

UK Air Defence

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.[1]

references: Micro Decision, August 1983 Accountancy, March 1984 Information Systems. February 1986

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 (data input, validation and transmission) software. Nearly 450 validation rules ensured accuracy within and between various reports. The data were then transmitted to Ilford where a HP3000 used Fortran software for consolidation and reporting - also on HP125s.

Plessey were among the first firms to use computers. Their Training Department developed an interactive management game (PITDEX) using TeleType printer/keyboards to link to LEASCO computers in the States via standard telephones and acoustic couplers.

In 1967 or 1968 English Electric was subject to a takeover bid by Plessey, but chose instead to accept an offer from GEC.

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.[1] 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.

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.[1] 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 15,000 people by 1986.

Plessey Electronics logo

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. 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.[3][4] In the 1960s the Group continued to expand, setting up facilities at places such as West Leigh Havant Hampshire and Templecombe.

At the end of the war the company's orders dropped from £5 million in 1944/5 to only £263,000 in 1946. The workforce fell to less than 6000. Radio and television sales were the main area of activity until the renewed demand for defence products with the Korean War. From a turnover of £5 million in 1949/50 there was an increase to £32 million in 1959/60.

Post World War II

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.[1] The company also built a new factory at Swindon, and opened several other shadow factories around the country producing munitions. Caswell became the location for Plessey's first dedicated research centre in 1940. The wartime workforce of Plessey grew to over 10,000 people.

During the war, 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 (receiver), and T1154 (transmitter). In all 161,500 pieces of electronic equipment were produced.

Second World War

R1155 Receiver on top of T1154 Transmitter.

Aircraft components was another market into which Plessey 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 (an explosive cartridge device used to start aircraft engines), and Pump Engineering Services Corporation for the manufacture of Pesco fuel pumps. Plessey went on to produce large numbers of Pesco fuel pumps for Rolls Royce Merlin engines, and in 1940 the fuel pump for Britain's first jet engine was also supplied by Plessey.

Aircraft components

The manufacture of electrical components also became a key area of growth for Plessey. A vast array of different components were 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.

During the 1920s Plessey began to diversify into electrical manufacturing. Important contracts included the manufacture of early radios[1] for Marconi and the production of telephones for the GPO. Because of the increased production, Plessey moved to Vicarage Lane Ilford in 1923.[1] In 1929 the television pioneer John Logie Baird had his first production televisions produced by Plessey.[1] The company also produced the first British made portable battery radio in the same year.

Electrical manufacturing

both of whom rose to prominent positions in the company. [2], and Michael William Clark,John Allen Clark followed later by his sons [1]