This is a free one-day event at Imperial College, http://www.doc.ic.ac.uk/game/
To quote their website:
"Imperial College's Games and Media Event aims to bring together people from industry and academia in order to discuss some of the technical problems and solutions within the entertainment industry. This year's event will consist of a day of talks intended to inspire discussion and collaboration between industry and academia."
It's a quite casual and fun event, with a nice selection of industry and academic speakers. I (Robin) have been to it for the last 4 years and it was always well worth it (did I mention there's free food also?).
Please sign up on their website as seating might be limited.