British Computer Society
The British Computer Society (BCS) is the industry body for IT professionals, and a chartered engineering institution for information technology (IT).
http://www.bcs.org/bcs

Construction Industry Computing Association (CICA)
Dedicated to promoting the effective use of information technology in the construction industry.
http://www.cica.org.uk

HP/Works - HP/Apollo Technical Workstation User Group
UK-based technical user group for HP and Apollo systems.
http://www.hpworks.org.uk/

IT Europa
Provides information, news, and research on the European I.T./PC channel.
http://www.iteuropa.com

London Advice Services Alliance (LASA)
Designed for those providing advice and information services.
http://www.lasa.org.uk

M Technology Association - United Kingdom & Ireland
Dedicated to further the utilisation, improvement and understanding of the M Technology language , and also InterSystems CACHÉ that has backwards support for it, by disseminating related information on a world-wide basis.
http://www.camta.net

National Computing Centre
Membership and research organisation with the aim of promoting the effective use of information technology.
http://www.ncc.co.uk/

Network Professional Association
Non-profit association for professionals in network computing.
http://www.npanet.org

Society of Information Technology Management (SOCITM)
The Society of Information Technology Management was founded in 1986 as the professional association for ICT managers working in and for the public sector.
http://www.socitm.gov.uk/public/default.htm

Worshipful Company of Information Technologists
Promotes industry standards with a focus on the City of London and charity.
http://www.wcit.org.uk