
ADS Group Limited, informally known as ADS, is the trade organisation representing the aerospace, defence, security and space industries in the United Kingdom. It has more than 1,000 member companies across its sectors, including some of the UK's largest manufacturers, like Airbus, Rolls Royce, BAE Systems, Meggitt PLC and GKN.

Banham Group is a family owned security company. Established in 1926, Banham Group is now the largest supplier of burglary and fire prevention systems in London.

Chubb Fire & Security is a fire and security subsidiary of Carrier Global.

G4S is a British multinational private security company headquartered in London, England. The company was set up in 2004 when London-based Securicor amalgamated with Danish firm Group 4 Falck. The company offers a range of services, including the supply of security personnel, monitoring equipment, response units and secure prisoner transportation. G4S also works with governments overseas to deliver security services.

Group 4 was a security business operating primarily in the United Kingdom and latterly worldwide.

Intelligent Limited is a Holding Company and Parent company headquartered in Gloucestershire, United Kingdom and was incorporated on 21 May 2008. Intelligent Limited provides a group management structure for four companies and was born out of the operations of International Intelligence Limited, a company specialising in Intelligence, Counter Espionage and TSCM sweeping.

International Intelligence Limited is a United Kingdom based security and intelligence company. Incorporated on 11 July 2002, it is part of the Intelligent Limited group of companies that investigates and provides counter espionage services.
Rock Steady Group was a group of companies that was involved in stewarding and security at many major events in the United Kingdom. The three companies were Rock Steady Event Services, Rock Steady Sport Event Services and Rock Steady Security. The Group had a head office and operations office in Edinburgh with additional operations offices at Glasgow, Sheffield & Manchester.

Secom Co., Ltd. is a security company in Japan. It has operations in Japan, United Kingdom, Australia, New Zealand, South Korea, Taiwan, China, Thailand, Vietnam, Malaysia, Singapore, Indonesia, and Myanmar.

Securicor plc was one of the United Kingdom's largest security businesses. It was once a constituent of the FTSE 100 Index but merged with Group 4 Falck in 2004.

The Westminster Group plc is a worldwide security company that specialises in Fire, Safety, Security and Defence. The firms' headquarters are at Westminster House, Blacklocks Hill, Overthorpe, near Banbury, Oxfordshire, United Kingdom. The group operates through a network of over 70 agents and international offices in over 45 countries, with a slightly growing customer base consisting of predominately: governments and government agencies, embassies, non-governmental organisations and blue chip commercial organisations.