Ok, this one is just speculation but it can't be far off now can it? Can it!? Gallifrey's been missing in a pocket universe since The Day of the Doctor and, as of Series 8, the Doctor is no closer to tracking it down. Missy did tease him by giving him the coordinates but they turned out to be fake. Let's hope his next attempt - or at least the one after that - is the real deal. For God's sake, let him go home.