It is suggested that Leagram deer park was created at sometime before the 1340s. In 1356 and 1362 it is mentioned in the Calendars of Patent Rolls as belonging to John of Gaunt, Duke of Lancaster, and as one of several parks where the Duchy were to receive deer from.

Patent Rolls are records of the monarch's commands, or Letters Patent, which were written on parchment and stitched together in long rolls for each year. They are stored at the National Archives.