In the thirteenth year of the reign of Henry IV, John Rykone was brought before the mayor's court in London, accused of committing an act of forgery. Instead of operating as a conventional forger by fabricating a false document, Rykone chose a different method for committing his crime. He directly appropriated the identity of another man, John Dyce, and convinced a scrivener to draw up a bond in Dyce’s name, to the sum of £10. Rykone's act of identity theft exemplifies an intriguing category of criminal acts committed in the city of London in the Middle Ages: acts of identity fraud.

In a city the size of London, which by 1400 had a population of around 40,000, identity could be manipulated, misrepresented or misappropriated with relative ease. This study draws on cases prosecuted by the mayor's court in the late fourteenth and early fifteenth centuries in which a number of individuals allegedly committed such acts of identity fraud. Their crimes fell into different categories. Most resonant with modern concerns about the vulnerability of personal identity were the thieves who directly appropriated the identities of other named individuals. A second category included those who fraudulently altered their identities while begging, taking on new personae or adopting various characteristics to evoke the sympathy of passers-by. Into the final category fell the pretenders, who posed as officials of royal or civic institutions for financial gain. While published research into crime and criminality in the Middle Ages has touched on such actions, particularly on the behaviour of fraudulent beggars, this essay will treat all three categories as examples of a single phenomenon of identity fraud. Taken together, these cases display similarities: all involved men pretending to be someone they were not, whether by taking the name of another person, fraudulently posing as a worthy recipient of charity or acting as a legitimate office-holder. These acts of criminality expose the fragility of the system of identification in the Middle Ages and demonstrate that there were few effective ways to establish the identity of an unknown outsider.

Most research on imposture in the late Middle Ages has focused on the high profile cases of royal pretenders, such as Perkin Warbeck and Lambert Simnel. Their acts of imposture have warranted attention for their national and international political ramifications, and have very little in common with more quotidian acts of identity fraud.