There's very little natural wilderness left in Britain. Sea cliffs can come close, as can mountain tops above 3000 feet. True ancient woodland is rare. On Dartmoor, Black Tor Copse and Wistman's Wood come close, as does the stunted oak forest of Dizzard, about ten minutes from my house. The sad fact is that any area determined as natural is inevitably surrounded by less natural habitat and subject to invasive interference therefrom. Great swathes of heather moorland may look very nice in August but they are no more "natural" than a field of waving corn.