Speculation time! I'll have a go.
OPM UK made comments about a "super sexy secret game" being announced at TGS.
http://www.qj.net/OPM-Sony-s-super-sexy-secret-game-will-be-revealed-at-TGS-next-month/pg/49/aid/124410
I did a bit of investigation into this and I am certain this is the game the BBC guy has been going on about.
From what I understand, it was shown behind closed doors at the Game Developer's Conference in February (when the BBC man, Darren Waters, first started running his mouth about it) then shown again behind closed doors at E3.
http://whatifgaming.com/scea-hides-new-game-up-sleeve-closed-door
Two of the moderators over at Eurogamer forums (one of whom is the sites owner and founder, Rupert Loman or "rauper") claim to have seen the game alluded to by Darren Waters. They refused to go into specifics about it, but they did confirm that they were shown a gameplay trailer and not prerendered CG.
Nobody has a clue who the game is being developed by, but the vague descriptions about this project seem like nothing Team Ico would produce (a guy in a black Crysis like suit? Immersion and storytelling that push the envelope? Sounds nothing like Team Ico, they favour more enigmatic forms of storytelling) and shortly after GDC in February there were suspicious noises about a Liverpool developed action game.
And now herein lies the problem/mystery: all of the (admittedly vague) signs point towards this game being Western developed game, so why the hell is it being announced at an eastern game show?