We have Mischief Night, but it takes place the day before Halloween (October 30th), and the pranks typically lead to vandalism instead of harmless little pranks. The tradition has died down a bit though within the last 10-15 years.
Now, how many people in Britain actually celebrate Halloween? I’ve heard it’s sorta big in Scotland and also all around Ireland, and that’s it had been growing a little bit in England.
I’d also like to add that it’s possible some Guy Fawkes traditions influenced the current Halloween tradition in the USA and Canada.