Thomas Brewster's mother committed suicide in 1851, jumping off a bridge into The River Thames. It was claimed at her funeral that she did this due to the burden and shame that giving birth to her son, 4 or 5 years earlier, had brought upon her.
After her death, a being from a potential future used her form to convince Thomas Brewster to do its bidding, in an attempt to make its potential future a reality. (AUDIO: The Haunting of Thomas Brewster)