Mick Huff

 was a security guard on Coulton Salt Mine. He kept seeing children running around on the site but looking ethereal, one had the appearance of his son. The Miniaturist used this memory to trick him. He found Dodo Chaplet and the missing buildings. The First Doctor got the Miniaturist to take on the form of Mick's son so that he could say goodbye to him. (AUDIO: The Miniaturist)