This was very interesting. The wiki entry says:

> Historians, poets, and lawyers speak of the Medieval law associated with the curfew bell as being levelled mostly against the conquered Anglo-Saxons. It was initially used as a repressive measure by William I to prevent rebellious meetings of the conquered English. He prohibited the use of live fires after the curfew bell was rung to prevent associations and conspiracies. The strict practice of this medieval tradition was pretty much observed during the reign of King William I and William II of England.[7] The law was eventually repealed by Henry I of England in 1103.[8]

Also:

> The English word curfew is from old French carre-feu or cerre-feu.[2] These initial French words later derived into couvre-feu.[2] The word was again later turned into cover-feu in the Norman language after the conquering of the English.[6] Each of these meant to cover the live flaming fire.

There's a horror novel called Curfew by British author Phil Rickman, that heavily features a village's need to honor an ancient curfew. From goodreads:

> On the border between England and Wales lies the tiny town of Crybbe, not picturesque enough for the tourist trade, quietly sliding into decay. Max Goff means to change all that. Goff has made millions in the record business, but his heart is in New Age philosophy. He has learned that Crybbe was once a spiritual center of sorts, surrounded by ancient standing stones that were emblems of power. He means to replace the stones that have fallen - or been destroyed, as many of them were - and establish a thriving New Age community that will draw tourists and students from all over the world. What Max Goff doesn't know is that the standing stones of Crybbe were destroyed in the sixteenth century for a very good reason. Some of the endearing customs of the town - such as tolling the church bell for curfew each night - are actually deadly serious rituals. The people of Crybbe know that evil has been kept at bay here by the old ways, and that there's nothing quaint about them. And the power about to be unleashed by Max Goff is nothing like the soothing music and herbal remedies he associates with the New Age. This is the power of the old age, pent up for centuries and about to be released with deadly fury!

I'm subbed to /r/horrorlit and talk up the very talented Phil Rickman at every opportunity.