Some people claim the Problem has always been with us.  Ghosts are nothing new, they say, and have always behaved the same.  There's a story the Roman writer Pliny told, for instance, almost two thousand years ago.  It's about a scholar who bought a house in Athens.  The house was suspiciously cheap, and he soon discovered it was haunted.  On the very first night he was visited by the Specter of a gaunt old man in chains.  The Visitor beckoned to him; instead of fleeing, the scholar followed the ghost out into the yard, where he saw it vanish into the earth.  The next day the scholar had his servants dig at the spot.  Sure enough, they soon uncovered a manacled skeleton.  The bones were properly buried, and the haunting ceased.  End of story.  A classic Type Two ghost, the experts say, with a classic, simple purpose - the desire to right a hidden wrong.  Just the same as the ghosts we endure today.  So nothing's really changed.

Sorry, but I don't buy it.  Okay, its a decent example of a hidden Source - we've all known plenty of similar cases.  But notice two things.  First: the scholar in the story doesn't seem at all concerned that he might be ghost-touched, and so swell up, turn blue, and die a painful death.  Maybe he was just stupid (not to mention lucky).  Or maybe Visitors back in ancient times weren't quite as dangerous as they are now.

And they certainly weren't as common either.  That's the second thing.  The haunted house in Pliny's story?  It was probably the only one in Athens, which is why it was so cheap.  Here in London there are dozens of them, with more springing up all the time, no matter what the agencies do.  In those days, ghosts were fairly rare.  Now we've got an epidemic.  So it seems pretty obvious to me that the Problem's different from what went before.  Something strange and new did start happening around fifty or sixty years ago, and no one's got a damn clue why.

If you look in old newspapers, like George does all the time, you can find mentions of scattered ghostly sightings cropping up in Kent and Sussex around the middle of the last century.  But it was a decade or so later that a bloody series of cases, such as the Highgate Terror and the Mud Lane Phantom, attracted serious attention.  In each instance, a sudden outbreak of supernatural phenomena was followed by a number of gruesome deaths.  Conventional investigations came to nothing, and one or two policemen also died.  At last two young researchers, Tom Rotwell and Marissa Fittes, managed to trace each haunting to its respective Source (in the case of the Terror, a bricked-up skull; in that of the Phantom, a highwayman's body staked out at a crossroads).  Their success drew great acclaim; and for the first time, the existence of Visitors was firmly imprinted on the public mind.