New UK calling abroad MVNO: Now Mobile
 

A new MVNO has launched, not sure what network it runs on but its another one aimed at those who call abroad.

Details here: Now Mobile

Now two others...

GT Mobile - New GT Mobile SIM | Fantastic low rates |Register Now! | GT Mobile Point of Sale | Top up GTMobile SIM (Run's off of Vodafone)
iCard Mobile (No idea who they run off!)

Also....(Almost forgot...)

Vizz Mobile

Dialog Vizz UK

Again no idea who they run off!