The Unexpected Arrival 13 (Parent!Lock)

"Angela gave us a box of his old possessions. Wouldn't hurt to rummage through." Lestrade dumped a large cardboard box of photos and children's toys and clothes onto his desk.
"How old was he when his parents died?" John asked, picking up a wallet of pictures
"Ten."
"Do you know how-" John leafed through the photos of the deceased as a toddler until he came across one that had been cut in half, "Wait, Lestrade come and look at this." The picture showed a woman in her mid to late twenties holding a baby that they knew was the deceased. The other half of the picture had been cut off, as if there was something that they didn't want anyone to see.
"I'll call Angela," Lestrade said, reaching for his phone, "Ask her if she knows what was in the rest of the picture." John put down the photos and pulled out some children's clothes. He felt fear and nausea rise as he was reminded of his own toddler. Until now he had managed to blank out those feelings but he could sense himself losing his cool. Lestrade put his hand over the phone so he could talk to John, "They'll be fine, Sherlock and Hamish. They'll be fine John."
John straightened up and let his expression go cold, "Yes. Yes they will." He folded the dungarees he held and placed them on the desk, before pulling out some more clothes from the box. "Um, Lestrade?"
"Yes?"
"There's two of everything," John held up two identical stripy red t-shirts to emphasize his point, "Lestrade, I think we need to speak to his doctor."


"It was a very strange case, yes." Dr. Hastings paced from one end of his surgery to the other, rubbing his chin in thought. "He had a scan not three months before that and there were no signs, then the next thing I hear, he's died."
"So he didn't come in between the diagnosis and the death?" John asked
"Well no. I didn't even diagnose him. Nor did I refer him to hospital. Like I say, it was a very strange case."
"I think we have all we came for, thank you." Lestrade said as he stood. The two men left the Brighton surgery and started making their way back to the train station.
"I have to call Moriarty, we only have two hours left. I think I know how he did it." John got out his phone and started to dial.
"Wait, you do?" Lestrade walked in front of John to stop him, "How?" The phone made the dial up noise and started ringing the unknown number, "John wait, what if you're wrong?"
"We don't have time to check, my son could be dea- Yes hello? This is John. We know how he did it."
"Tell me, John." John gasped as he heard that the voice on the other end of the line was Sherlock's.
"Robert Jones had an identical twin brother who was dying of cancer. Instead of divorcing his wife he used the brother that she didn't know about to fake his own death." The pause after felt so long. John's breathing started to quicken as doubts crossed his mind.
"Well done." Although Sherlock sounded relieved and almost proud, there was still a hint of fear in his voice, "Now you have three hours to find your son alive."
"What about Sherlock? Hello? WHAT ABOUT SHER-" The phone went dead. John turned to Lestrade, "Find Hamish."