After London by Richard Jefferies

After some sudden and unspecified catastrophe has depopulated England, the countryside reverts to nature, and the few survivors to a quasi-medieval way of life. Beginning with a loving description of nature reclaiming England -- fields becoming overrun by forest, domesticated animals running wild, roads and towns becoming overgrown, the hated London reverting to lake and poisonous swampland -- the rest of the story is an adventure set many years later in the wild landscape.
The meadows were green, and so was the rising wheat which had been sown, but which neither had nor would receive any further care. Such arable fields as had not been sown, but where the last stubble had been ploughed up, were overrun with couch-grass, and where the short stubble had not been ploughed, the weeds hid it.

Jefferies’ novel can be seen as an early example of post-apocalyptic fiction. After some sudden and unspecified catastrophe has depopulated England, the countryside reverts to nature, and the few survivors to a quasi-medieval way of life.

The first part, The Relapse into Barbarism, is the account by some later historian of the fall of civilisation and its consequences, with a loving description of nature reclaiming England. The second part, Wild England, is an adventure set many years later in the wild landscape and society.

The book is not without its flaws but is redeemed by the quality of the writing, particularly the unnervingly prophetic descriptions of the post-apocalyptic city and countryside.