This looks close to confirmed, although not officially. Kerry Ingram, a young English actor from Warfield (fitting!), has tweeted about getting a role on Game of Thrones. Darq(uemode) at SpoilerTV has some more details:
Kerry recently won an Olivier Award for her role in the musical Matilda… and worked on the 2012 film Les Misérables (cast by Nina Gold).
Hear Me Roar: It has to be for the role of Shireen, daughter of Stannis Baratheon. Kerry has a more than solid pedigree, and a definite Nina Gold connection, so now we are just waiting for a confirmation.