Hide all of this in a box, bury it within twelve acres of a birch tree, chant "i nunc amit me te amare simul lorem ipsum dolor sit amet quoque sicerit in me ex caritate," and, when he eventually dies a natural death, his undead body should return to you as a nightwalker.
But then came gaslight, and the city's secret life was now an invitation to the compulsive nightwalker.
By the end of the 19th century, the nightwalker had become a stock literary figure, although as Beaumont shows in a series of brilliant literary readings, if he was mobile in person he was equally hard to pin down in writing.
As early as the 12th century, the nightwalker appeared in a nervously extended list of the capital's social evils: "Actors, jesters, smooth-skinned lads, Moors, flatterers, pretty-boys, effeminates, pederasts, singing- and dancing-girls, quacks, belly-dancers, sorceresses, extortioners, night-walkers …" In his 1634 masque Comus, Milton referred to the "evil thing that walks by night".
The majority of its thousand-plus revelers are dressed in some sort of nightwalker get-up, all black leather or sanguine-ready white cotton.
But in addition to these figures, Beaumont points out, London's streets belong to the nightwalker, a "modern antihero" who spends the hours of darkness pacing through the city, whether this is because he is seeking himself (almost all the figures Beaumont discusses are male) or fleeing from himself.
Talk of the Town cartoon strip showing nightwalkers in the vicinity of City Hall: a taxi-driver eating at Park Row Lunch, the counterman at the Roxy Coffee Shop, the token-booth clerk at the Brooklyn Bridge Station, and the manager at New York Dolls, a topless bar.
They were created, of course, to provide practical information for gentlemen travelers venturing through a city's demimonde, and so have titles that range from mildly risqué ("The Pretty Women of Paris," "Directory to the Seraglios") to unashamedly coarse ("A Catalogue of Jilts, Cracks and Prostitutes, Nightwalkers, Whores, She-Friends, Kind Women and Others of the Linnen-Lifting Tribe").
For many years a curfew helped to promote the association of nightwalkers with felons (including streetwalkers) and demons.
Yet although Dickens was the undisputed king of the nightwalkers, he was not the last.
The "houseless", as they used to be called, had been an endemic presence in Europe's cities after dark since the middle ages, when male and female denizens of the streets were criminalised as "common nightwalkers".
