51 Degrees
Offers wholesale telecom bandwidth and local loop connectivity through dedicated fibre optic backbone network around London.
http://www.51deg.com/

Ision Internet
Provides site management, acces, hosting, domains, and commerce services.
http://www.ision.net.uk/

TWF Internet
Supplies InterLinx Linux-based access appliance, backup MX service, anti-virus email, and terabyte file servers.
http://www.twfinternet.com/