The Wanderer

An obscure writer disappears, a typescript is found. Is it fiction, perhaps the author's last novel, or something far stranger?

After obscure author of strange stories, Simon Peterkin, vanishes in bizarre circumstances, a typescript, of a text entitled, 'The Wanderer', is found in his flat.

'The Wanderer' is a weird document. On a dying Earth, in the far-flung future, a man, an immortal, types the tale of his aeon-long life as prey, as a hunted man; he tells of his quitting the Himalayas, his sanctuary for thousands of years, to return to his birthplace, London, to write the memoirs; and writes, also, of the night he learned he was cursed with life without cease, an evening in a pub in that city, early in the twenty-first century, a gathering to tell of eldritch experiences undergone.

Is 'The Wanderer' a fiction, perhaps Peterkin's last novel, or something far stranger? Perhaps more 'account' than 'story'?