From A London Child Of The 1870s, by M.V. Hughes

Adventures of a kind that were not forbidden mainly because mother didn't know about them were plentiful enough, and usually carried out in the back garden. One boy would dare another to some perilous act, while I was a delighted looker-on, half dreading and half hoping for the worst.

An acacia-tree stood at the end of the garden. Into this the boys would climb and then swing themselves over into the street--a considerable drop. Another feat was to walk along the top of the high, narrow wall, endowed with bits of glass.

The most dangerous of all was climbing round a ledge, some two inches wide, that ran along the house over the area. The boy who attempted this had to flatten himself, spread out his arms, and press his palms against the wall. this particular part of the back premises was invisible from any window, and was therefore chosen when we were 'sailing near the wind', as my father called any near approach to the sinful.

Presumably there was a potentially lethal drop involved. I used to know some neighborhood kids who would get up to this kind of stunt. Most of them lived.