As for the broader topic of Halloween and fakelore, here's what I think (and you can cut this out and keep it to refer to again at Christmas, when people start banging on about the holly and the ivy, the boar's head or w.h.y.).

Firstly, it's dark out there, and it's getting cold. This experience has been a big important experience to most people in most centuries, and - to a much lesser extent - it still is for us. The turning of the year is important, and seasonal rituals are a way of responding to that - even really naff, plasticky, made-up-y seasonal rituals.

Secondly, Celtic religion went out in Britain when the Romans arrived. Roman religion took its place - including the worship of dead emperors. Then that was replaced by Christianity. Then that was replaced by the Nordic religions of the Angles, Saxons and Jutes (people always forget the Jutes). Then that was replaced by Christianity, again. Many years later, popular Christianity was replaced, although it was replaced by another variety of Christianity. Many years after that, there was electricity and Darwin and Freud, and we all gradually stopped believing in anything, with Spiritualism as a kind of rearguard action for people who wanted to believe in something but couldn't buy into Christianity any more.

My point - I have got one - is that anyone coming to this subject cold would expect English seasonal folk customs to be based on the Christian ritual year, perhaps with some survivals from the older forms of Christianity which went out with the Reformation. And they quite clearly are - there's basically nothing to explain. The chances of anything surviving from the Celts are minuscule, and the evidence that anything has survived is slim to none.

Thirdly, I think it's worthwhile - or interesting, at least - to study New Age beliefs as a form of modern folklore in itself. The idea of the worlds of the living and dead touching or interpenetrating is an old one, and the sense that it might be happening at this time of year is part of an appropriate ritual response to the season. But if you got in your Tardis and told a pre-Roman Celt that the "veil between the worlds grows thin at Samhain" they wouldn't have known what you were talking about. Come to that, if you'd run the idea past Lady Gregory or Gerald Gardner, they would probably have been baffled too (although I'm sure they would have jotted it down). It's a very modern idea.