Art historians usually find little evidence for the nature of communication between patrons and architects in the Middle Ages. Scholarly opinion has often placed the burden of new design with masons, but over the course of the later twentieth century this claim has been revised and nuanced. This paper uses the evidence of wills and contracts in order to answer two questions: what techniques did medieval patrons use to describe their wishes to their masons; and how prescriptive were their requirements? Its conclusions suggest that patrons, even of local or parochial projects, could make highly specific and creative demands for new works, based on critical and perceptive judgements of recently constructed buildings in their local area. It recreates the discursive and disputatious design process adopted in several parishes as they planned, contracted and executed new church buildings.