When Anthony got home, Jonathon was missing, he assumed at the Roses' house. Anthony decided to do some thinking upon the matter of Watson's sudden ability to deduce. Not that he couldn't but that he did.
He thought of the possible teachers of deduction, the were only four, Sherlock and John are who knows where, James Moriarty s dead, the last possibility is Mycroft, Sherlock older brother and though quite old has a few tricks up his sleeve still. He can drive to wherever they would need to go for a deduction, for a lesson. He had a rather large house for someone living alone, which meant Watson could stay there when necessary.
Small things like this kept coming to his head and the last one unsettled him, Mycroft worked for the government at one point, what if Watson was training to follow Sherlock and Watson's footsteps in helping the police. It would be quite problematic.
He decided to follow into this investigation and left for Mycroft's. He noticed a few things as he closed the distance between him and the house, it was recently painted, there was a silver car in the driveway, the last thing he noticed was the horrible feeling he was getting. To him it was awful just to be close to his house.
He knocked at the door when he arrived and Mycroft still wearing his business like suits in his old age even, opened the door and invited him in.