Fairies have become an intrinsic part of the Christmas spirit.

Many families place a fairy on top of the Christmas tree. Fairy lights are everywhere in December.

Then there are Santa’s elves, the stars of so many Christmas films and stories on our televisions and in our children’s books and more recently the ‘Elf on a Shelf’ phenomenon.

But is it really safe to invite a Welsh fairy into your home?

Simon Young is the editor of Magical Folk: British & Irish Fairies – 500AD to the Present, which is the first history of fairy sightings in Britain and Ireland over a millennium and a half.

He discovered some pretty harrowing stuff about Welsh fairies.

“While some are benevolent, many of the magical folk Brits have encountered over the centuries are nothing like Hollywood’s tutu-clad, butterfly-winged miniature Marilyn Monroes meet J M Barrie’s Tinker Bells we commonly associate with them,” says Simon.

The first written occurrence of a Welsh fairy appears in c1500 where a poet complains of a relatively benign tylwyth teg – ‘fair family’ – and a spoilt tryst by a magician’s mist.

“Generally, those who over the centuries encountered Welsh fairies reported that they could be a scary lot,” laughs Simon.

“Their ways or ‘ffordd bendith eu mamau’ were unknown, capricious and suspect. Tey were hated with a vengeance by Puritan preachers such as Morgan Lloyd of Wrexham.”

According to Simon, Welsh fairies have a long history of pilfering food from the natives.

If they were to get into your home, they would likely feast on your Christmas goodies as they did to a husbandman in mid-17th century Wales – and they could get quite stroppy as they cavorted and made merry.

One story Simon recounts sees fairies visiting one Morgan William’s house where, finding no water for them, seized his wife who screams out in excruciating pain which he says was the prong of a “pikil or hayfork” in her thigh.

“A Welsh fairy would probably take a very dim view of your Christmas tree in the first place,” says Simon.

“Fairies have for centuries been associated with trees in Wales, particularly breninbren or ‘monarch’ oaks, which fairies loved to dance around.

“But a Welsh fairy did not stand on top of them to pirouette. They guarded them against humans and walloped those who damaged their charges and were hurt ‘even unto death’.

“If you heard all these goings in the middle of the night and were to come downstairs and protest as they revel around your Christmas tree, they might shoot you with an elf bolt.”

Throughout Simon’s book there are many reports of humans being punished harshly by them for interrupting or even watching fairy knees-ups. They don’t like to be seen by humans.

Can it get any scarier? Yes it can.

“Fairies very possibly would kidnap your children as historical sightings report they flew off with the souls of the young and replaced them with changelings,” describes Simons.

“The Welsh writer Edmund John Williams wrote his baby son was abducted and the fairies ‘left an edeot in his stead’.

“Welsh writer Edmund Jones wrote how in 1733 fairies abducted his own brother from a hunting party. ‘They took him from place and rendering him incapacitated’.”

You may well wonder how this lively lot became part of our Christmas traditions? The answer, according to Simon, is from the theatre and through the arts.

“British fairy madness kicked off two centuries ago on the stage when the grand urban houses ran pantomimes with large numbers of ‘fairies’: troupes of dancing and sometimes flying girls.

“These actresses and dancers were winged, dressed in white and occasionally had portable battery-powered electric bulbs attached to their heads or skirts.

“The theatre had picked up on the millennium-old association of fairies with glowing lights.

“Though these fairy lights, as opposed to their electric cousins, mislead humans at night with the fairies tricking their terrified victims into mires and swamps around our moors and wetlands.

“In the theatre the electric lights illuminated thighs rather than trickery.

“With an unusual amount of innocent Christmas flesh showing, theatre-goers took increasing pleasure in watching human perform as fairies.

“And this branded the fairy image into the minds of future generations of excitable theatre-goers. So much so that there was much concern in the press about fairy immorality.”

Although they’re now associated with the innocent charms of ‘elf on the shelf’, Santa’s elves are another set of wolves in sheep’s clothes.

“They are the perfumed, jollified version of the terrifying soul-stealing trolls the Vikings talked about,” says Simon.

“Needless to say, Viking originals were more likely to eat children than spend their time wrapping presents ‘for good boys and girls’.”

Writers started bowdlerizing this rowdy lot of Scandinavian tourists around the same time as electrical lights turned up.

Santa and his elves began to appear tapping away with hammer in poems and stories. Then, later they turned up in paintings and, by 1932, in cartoons and performances with fairy ballerinas.

So yes, why not put a harmless Hollywood fairy on your tree and drape those electric lights around the house.

But if you do see a British fairy near your home, close the shutters, stay inside and avoid a nightmare.