Dgc1808 on 30 January 2013
Are you leaving support studios out? If not then there's SONY Foster City and XDev Europe.
Also, I'm not sure if it counts but there's also Cellius. It's a joint venture between SONY and Namco that started in March 2007. They're main things is research of game technology but they are considered a game studio and they did develop Ridge Racer Vita.
EDIT: Oh, Studio Cambridge is now a subsidery of Guerilla Games and is now known as Guerilla Cambridge.
4 ≈ One
