This thesis utilises the data sets provided through the recording of historic graffiti within secular and religious buildings to analyse and draw a theoretical understanding of behaviour within Medieval Christian religious practice during a period of intense pilgrimage activity. The work focuses on the South of England and questions the nature of personal religious engagement within the church and cathedral specifically looking at the methods used by lay worshippers to gain independent access to the divine.To facilitate this study large volume of historic graffiti data has been recorded in Hampshire, Wiltshire, and West Sussex. This data has been analysed using geostatistical models to assess distribution and relative nearness of the marks to both known points within the built environment and to neighbouring marks. This data has then been compared to existing literary and historical texts to understand how the marks have interacted with personal prayer practice and the built landscape.The outcome of this study has been the generation of a theoretical framework that describes one form of interaction using graffiti as ritual doing within the generation of personal rituals of encounter that facilitate the exploration of a complex nested ontology within the built landscape. This nested ontology provides access to the divine in a ritually safe manner and permits lay worshippers to navigate the spiritual dangers an encounter with the divine without the guidance of a ritual authority.