The old Cornish word "Bucca” belongs to the same family of words as the Irish "Pooka" and the Welsh "Pwcca" meaning a person of a mischievous disposition, one about whom there is something weird or wisht (in the old-fashioned magical sense), and also a frightful apparition. Bucca-dhu is a black spirit and Bucca-gwidden a white spirit.
There is a story told of an old lady who lived long ago in Cornwall who was so fond of card-playing that she would walk almost every winter's night, in spite of wind or rain, to a nearby village that she might enjoy her favourite pastime.
The old lady's step-daughter wished to put a stop to what she regarded as a rather scandalous past time, as the old dame seldom arrived home before the small hours of the morning!
With this in mind she persuaded a local lad to array himself in a white sheet to impersonate a ghost that was often seen wandering about a lonely spot over which the old dame had to pass. This was to scare her so witless she'd never walk that path again and thus bring an end to her card-playing proclivities.
The winter's night was dark and rainy when at about midnight he seated himself on a stile, whereupon he had to wait another two or three hours; the dear old lady was in no hurry to leave such pleasant company!
At last she passed by, seated herself to draw breath, and sensing some mischief upon seeing the white figure said,
"Hello Bucca-gwidden, what cheer? And what in the world dost thee do here with the Black Bucca-dhu so close behind thee, ready to take you away to his firey realm?"
That an evil spirit might be right behind him so frightened the young lad that he ran off as fast as he could lay feet to ground, throwing the white sheet into the brambles at his side. The old lady scampered after, clapping her hands and calling,
"Well done Black Bucca-dhu, now thee will catch White Bucca-gwidden and take him away with thee!"
Of course the old lady was playing a fine trick on the young man who was so frightened he fell into a fit and was never right in the head again, thus becoming a real Bucca, as was wont to happen in the olden days when folk were far more suceptible to visitors from the spirit realm than us lot today with our heads immersed in tweets. So, the strong-minded, sociable old lady enjoyed many more years of her favourite past time and in fact her descendents still live in the area to this day.