Bucolic Sussex countryside, England in the 1950s/1960s
We just had to squeeze the word bucolic in there. It's the best, right? It sounds like a cross between a vegetable and an unpleasant digestive disorder, but refers to how beautiful and calm the countryside can be. What's not to love?
Anyway, our story takes place, as best as we can tell, during the late 1950s or early 1960s in the beautiful countryside of Sussex. The boy's house is surrounded by a considerable amount of garden (which in England can mean both yard or where flowers go, which to us Yanks can be kind of confusing). It's beautiful, but also pretty costly to maintain.
Just down the road is the Hempstock farm, which may or may not occupy more land than its neighbors realize due to some kind of supernatural loophole. Either way, these kids live out in the middle of pretty much nothing but fields, trees, and bucolic countryside (ha—there it is again).
This is important to note in that it helps to set up a scenario of isolation that makes this tale more likely and believable. If all of this stuff happened in Times Square you'd better believe that "fleas" and "varmints" would've gained more international recognition, especially if it happened in the age of cellphones and social media—there would be Vines all over the place. But by setting our story out in the middle of nowhere during the age of rotary phones and rabbit-ear antennae, it's actually conceivable that these things happened without anyone else noticing.