It's a growing trend, from what I understand, but hasn't yet reached the mammoth proportions that are found in the US.
I think part of the difference is that the UK already has it's harvest based festivities covered. The celebration of Guy Fawkes or Bonfire Night fills the void of Halloween in America. Just a week after Halloween, Guy Fawkes Night is a tradition that involves fireworks and a giant bonfire. It's a British institution in a way that Halloween doesn't seem to be.
When it comes to Halloween, there are no shelves full of individually packaged "fun-sized" candy. There are a few decorations available, but not nearly to the level of that found in America. Not a single house in our neighborhood is decorated- at least on the outside (and I doubt on the inside).
The only costumes I've seen are the cheap drugstore kind. And they're mostly scary. Not cute or funny. I guess they take the ghoulishness of the holiday seriously. I think that may be the main difference. In America, the focus is on little kids dressing up and being adorable and getting candy, with a soupcon of "scary" (mostly the kind that isn't really scary). In England, I think the focus on the scary means that it isn't really appropriate or geared towards little 'uns, so they don't really know what to do with it.
A cute little ballerina for Halloween.
I didn't actually start dance lessons for a couple of years, but the dream was already there!
I saw the following costumes today:
1. A cute little boy (~5 yrs) in a skeleton jumpsuit at the grocery store.
2. A sweet little witch (~4 yrs) walking along the road with her mom.
3. A young man (~20 yrs) dressed in a wedding dress and veil with zombie makeup being dropped off at a bar by his girlfriend.
4. A pack of 6 or so teen girls (~15 yrs) dressed in tattered school girl-ish outfits and drippy blood and pale makeup in the bathroom at the grocery store (What!? I'm pregnant.) fixing their faces and teasing their hair.
That's it. Not a single other costume in sight, despite the fact that I was in very busy parts of town at various times of the day. I didn't see any packs of kids and parents out trick or treating in our neighborhood either. It's the kind of area that it perfect for it too! Ross says that Brits don't know the rule about leaving your porch light on as a sign that you are open to candy-seekers, so I think it just all seems too complicated.
Also, the phrase "trick or treat" seems to cause some confusion. Whereas in America, everyone knows it's just what you say. It's really just means "give me some candy please". In England, it's less clear. What is this "trick"? Do you retaliate if the people don't have candy to offer? Again, I think it's the dark nature of Halloween in the UK. The people are searching for the ominous and creepy element, whereas Americans are happy to turn it into a more cartoony version of it's original incarnation.
Thus ends my ramble on Halloween in the UK. You can blame reader Elizabeth if you didn't enjoy it, because she requested it! :)