Be warned this list is very old and some of these agenices may not exist anymore.
National IT Employment Agencies
@MG
Best International
Capita
Capital Software
Computer Futures
Computer People
Daylight Resources
DP Connect
Elan
Huxley
IT Human Resources
IT Staff Search
Jenrick CPI
Modis
Pathway IT
Paragon
Progressive
Real IT Resourcing
Recruit First
Local IT Agencies (Cambridgeshire)
Cambridge IT Recruitment
Connect Resourcing
Cooper Lomaz
IdealPeople
ECM
Technical Recruitment
PCR
Vision IT
Job Search Engines
Cambridge Network
Jobserve
PlanetRecruit
TopJobs.com
Computer Weekly