I found this story in the Jeff Kacirk's "Forgotten English" calendar from October 31st, 2013.
"Phantomnation" is merely the appearance of a phantom, although to me it just sounds like a mild expletive. I stubbed my toe? PHANTOMNATION! It probably would have changed the dignity of The Phantom of the Opera if Christine screamed this every time the Phantom appeared.
Anyway, according to William Henderson's Folk-Lore of the Northern Counties of England, 1866, this was a very particular thing which could happen only on Halloween (of course), and only to maidens who lived near the border of England and Scotland (I'm sure it was just because this folk-tale grew up in that area, and not because phantoms have some sort of preference for women in Northumberland and Cumbria). He says:
"On Hallowe'en, a Border maiden may was her sark [nightshirt, or any undergarment that you would sleep in] and hang it over a chair to dry, taking care to tell no one what she is about. (Wait, if she washes her nightshirt, what is she sleeping in? Is she naked?) If she lie awake long enough, she will see the form of her future spouse enter the room and turn the sark.
"We are told of one young girl who, after fulfilling this rite, looked out of bed and saw a coffin behind the sark; it remained invisible and then disappeared. The girl rose up in agony and told her family what had occurred, and the next morning she heard of her lover's death. In another instance, the young woman is said to have seen her lover at first, but this image quickly vanished and was replaced by a coffin; she was shortly afterwards married to the man, but he soon died and left her a widow. I have heard of precisely the same practice in Ireland and in the county of Sussex".