A vision of an England covered with wildwood is not unprecedented in literature. The Anglo Saxon Chronicles refer to 'Anderida', a remnant of ancient woodland that once covered Southern England:
491: Aelle and Cyssa beseiged Anderida, near Pevensey, and killed all who were inside, so there was not one Britain left.
Although this describes Anderida as a defensible place, a hill-fort, the word refers to the Great Forest of the Weald – a place outlaws could escape to. In the eighth century, the Chronicles record that Sigebert, a deposed king of the West Saxons who had committed murder, fled into "Andred," and was slain. Robert Furley, describes the roots of the word, in his work The Early History of Tenterden:
Many places now bear very different names from those they once bore. What is now known to us as the Weald, which signifies in Saxon a woody country or forest, was known to the Britons as Coed-Andred, Coed being the British word for wood. The Romans called it Silva-Anderida. The Saxons called it Andred, Andredsley, and Andredsweald, and it retained the name of Andred for centuries after the Romans abandoned Britain. In our earliest Anglo-Saxon charters it is called sometimes Saltus-Andred (a country of wooded glades), Silva-Andred, Saltus-Communis, and Silva-Regalis. The name Andred was given to it, according to Lambarde, from its vast extent; Andred is in British "great or wonderful." One of our modern writers, Dr. Guest, says it signifies "the uninhabited district," from "an," the Celtic negative particle, and "dred," a dwelling; another modern writer (the late Mr. Lewin) says Anderida signifies "the black forest," from "an," the, "dern," oak forest, and "dy," black; while a third (Mr. Edmunds) says Andred is often met with as an owner's name. All this shews what little dependence is to be placed on nomenclature.
Archaeologia Cantiana Vol. 14 -1882 p 38
THE EARLY HISTORY OF TENTERDEN by Robert Furley, F.S.A.
Hilaire Belloc, in his poem 'The South Country', refers to this landscape:
The great hills of the South Country
They stand along the sea;
And it’s there walking in the high woods
That I could wish to be
An old saying states a squirrel could leap from tree to tree from Nottingham to the South Coast, and considering the vast stretches of primal woodland that covered Great Britain from the end of the last Ice Age until the millennium, this is quite probable.
It only takes 150 years for a forest to re-establish itself. If all the sheep and cattle stopped grazing tomorrow, in a century and a half the country would be covered by trees again. In After London, Jefferies estimates it to be thirty years – within a generation.