Part of the show Big Bang, Ghosts & The Paranormal
In Mill Road in Cambridge last Halloween I was out trick or treating with my daughter. We arrived at a door and mother and daughter came to the door, with another little girl who didn't speak at all, and was dressed in a Victorian dress which is what I thought was her costume. A few days later I asked the mother who this little girl was, she said no one else had been there - but myself and my daughter had clearly seen her.
This is interesting because most sightings of ghosts last between 5 and 30 seconds. But this this lasted longer if you saw her the entire time you had a conversation. You couldn't see her feet, which is also a give-away because ghosts don't usually respect floors ! If it is real it sounds like this was someone who probably lived in this house previously. If I were you I would find out a bit more about who lived there and see if it ties up, but a sighting of this duration would certainly raise eyebrows !