What is a British Film?

The current hype around the premiere of War Horse, followed by Spielberg's claim that this is his first 'British' film, begs a few questions.  Can a film made by probably the most famous American director of his generation ever truly be a 'British'film? OK,the novel on which it is based was written by a British author and is set in Britain (as well as France).  The screenplay was written by Richard Curtis, whom we have to thank fopr such gems of British cinema as Four Weddings and a Funeral, Notting Hill, Love Actually etc, which portray a Britain - or more accurately an England - far removed from the everyday reality of most souls in these islands, but very popular with American audiences.  The Wikipedia entry for the film lists it as American, despite the largely British cast and in terms of distribution and finace it is grounded firml;y on the other side of the Atlantic.  So in terms of it being the latest chapter in terms of our national cinema, I would disagree.  The film is aimed firmly at an American audience first and foremost and Spielberg's knowledge of Britishness is bound to be skewed by tha fact that he isn't one of us.  That's not a criticism of him, just a fact.  True British cinema is by one of us speaking back to one of us, surely?