Abstract The medieval abbey at Whitby, North Yorkshire, controlled a jurisdictional immunity from royal administration, which was territorial and was known as the Liberty of Whitby Strand. Since Frederick William Maitland, historians have analysed such jurisdictional immunities as an index of royal authority and power. However, the surviving documentation for jurisdictional immunities means that it is often difficult to establish precisely when they were created or what franchises they included. Whitby Abbey claimed that the Liberty of Whitby Strand originated in a grant of King William I and this was accepted by the Victoria County History at the beginning of the twentieth century. Since then, the Liberty has been almost completely ignored. This article revisits the evidence, suggesting that it is possible to pinpoint its origins with rare precision. It argues that the Whitby monks forged a series of charters to persuade King Richard I and King John to transform a narrower portfolio of franchises into the wider territorial Liberty. This article further considers the politics surrounding its creation under Richard and John, and its implications for our understanding of royal authority and power.