John: Mrs. Hudson… Why did Sherlock think I’ll be moving back in here?
Mrs Hudson: Oh he put your chair back again, isn’t he? It’s nice… Looks much better.
My head-canon on the Watson-chair? It was in Sherlock’s bedroom, by the bed, which is why he didn’t want anyone going in there. He’d set it up so he could go to sleep imagining John was still there, maybe quietly reading a book or having a cuppa. When he thought John might be coming back (obv due to Mary issues), he put it back where it was previously.
You guys all realize there’s another possible reason for why Sherlock moved John’s chair, don’t you?
He just didn’t want anybody but John to sit in it.
John is always welcome at Baker Street, but like HELL Sherlock will ever allow some client to swan in and plop themselves down in JOHN’S CHAIR.