Hehe! I also like to think Q is the reason Sherlock got into Baskerville without immediately tripping alarms. 'No, this man who completely does not look like his ID photo is totally cool to let into your super secret base.'

I have most of a fic with what Q was doing during Reichenbach, but the timeline is so messed up in the episode that I can't actually figure out how Sherlock did everything he needed to, so I can't really decide when Q did everything he needed to.

I'm also retroactively deciding that Sherlock figured out the code in Blink Banker thanks to Father's lessons.