Sherlock’s Scandal in Belgravia deduction

There’s a margin for error but I’m pretty sure there’s a Seven Forty-Seven leaving Heathrow tomorrow at six thirty in the evening for Baltimore. Apparently it’s going to save the world. Not sure how that can be true but give me a moment; I’ve only been on the case for eight seconds. Oh, come on. It’s not code. These are seat allocations on a passenger jet. Look: there’s no letter ’I’ because it can be mistaken for a ’1’; no letters past ’K’ -- the width of the plane is the limit. The numbers always appear