The festival we now call All Hallows' Eve existed in obscurity for centuries, celebrated by pagans, the Celts, and the odd witch and wizard. But Irish believers fleeing the Potato Famine took it to the US, where the Americans got their teeth into it. Before you could say 'marketing opportunity', it was on our shop shelves - usually by August. As if by magic, it is now the third most profitable event for UK supermarkets, after Christmas and Easter. Last year, UK consumers spent £120m on Halloween - a massive jump from £12m in 2001. In the States, festival fans spent an astonishing $3.3bn in 2005. Now that's scary. As a Woolworths representative said: 'It's no longer a matter of a few plastic fangs.' Partygoers expect themed food, drink and decorations and increasingly elaborate costumes, while trick-or-treaters need to be kept at bay with hundreds of thousands of pounds' worth of sweets, paid for by beleaguered home-owners. Kerching! A survey of adults' Halloween costumes in the US in 2005 found 3.9 million witches, 513,000 zombies and 271,000 pimps wandering the streets - sounds like an average night out in south London. But not everyone will be bobbing for apples come the 31st of the month. In some parts of Britain, this face-dunking has been replaced (through fear of saliva-borne germs) by standing over a bowl with a fork in the mouth, trying to skewer an apple. And so another perfectly good tradition bites the dust.