In the UK census we ask people what religion they follow. An analysis has been published recently going into some of the detail behind the headlines which were that the proportion of people identifying as Christian had dropped below 50% for the first time and that the number ticking the box marked "No religion" had gone up significantly.
The really interesting bit for me is that the data has been published in map form down to the level of "Output Areas" (England and Wales only) - these are the smallest geographical areas that they use, for reasons of confidentiality and identifiability of individual subjects or households. An Output Area is usually about 100 households (it varies widely depending on the geography of the area, but this is a rough average). So you can zoom in to a fairly detailed level to see what the reported religious make up of a few streets is. In the case above, Rushmoor in Hampshire has one of the highest proportions of Buddhists in England and Wales and this little part of Mayfield would seem to have one-in-ten identifying as Buddhist.
I think you have to take the results with a pinch of salt, since people in the UK are known to be "playful" with such questions. For example, the number who follow Shamanism has leapt this year to 8,000 (that's more than Rastafarians) from 650 in 2011. I have my doubts about that, but would enjoy being put right.