In ASIB we learn to associate Mycroft with the Queen (“are we here to see the Queen?” “Oh, appearantly, yes”). In the “spoiler promo pic” for TFP, Sherlock is throwing away chess pieces, most prominently the white queen.
Season four has also drawn our attention to the Queen in other ways. For example, Culverton talks about what would happen if the Queen was a serial killer (“I’d be the first to know, we have that kind of friendship”). And then there’s Moriarty, arriving at Sherrinford to the sound of ‘I want to break free’… by Queen.
If there is a Lost Special, those elements definitely point to M theory. Perhaps this has been said before. Definitely some people smarter than me can write great meta about this.