The point was once made on the ex-Mrs Pitt’s sitcom Friends that when on-screen sex between two actors is hot, their off-screen partners have nothing to worry about. It’s a limp and lifeless couple-up that only vaguely signals the real-life shenanigans. Another case of a pair who sizzle individually but (see the 2009 BAFTAs Red Carpet interviews) clunk as a couple.