Above notes were a result of reading the posts. Just watched TLD. Oh my.

I'll have to think about all this to fully address your theories but...Sherlock couldn't have gone out the window at the hospital and taken a wheel chair with him. And, we don't know he was as Leinster Gardens at the time he called John, just that at some point later they two of them were there together. I don't think Mrs. Hudson is complicit but like your idea that the Baker Street Irregulars might well have been at work. I also don't understand why John automatically assumed that Sherlock believed he was moving back in because the chair was back. He could have moved it back in response to John's earlier remarks about the chair being moved. We also don't know that Sherlock didn't return to the flat between the time he and John left earlier in the day - so Sherlock could shop for an engagement ring. He might well have returned to the flat before meeting John in the evening and could have moved the chair before he left to meet John at CAM's office. That just leaves the bottle of perfume. He would have had to obtain that between the time he left the hospital and meeting John at Leinster Gardens. Sorry, I'm rambling, but like you I love the episode and really enjoyed your post.

CAM didn't have photos of Mary. Remember, its just his "mind palace". Not sure where I'm going with this.