Trent Park is the site of a late eighteenth-century landscape park, lakes and woodland, once within the medieval hunting forest of Enfield Chase, and developed throughout the nineteenth and early twentieth centuries with gardens and pleasure grounds on the sides of Trent Park House (the Mansion House). The four key periods of the Mansion House development and garden-making were during the ownership of Richard Jebb (1780s), John Cumming (early 1800s), Francis Bevan (mid-late nineteenth century), and Philip Sassoon (1908–39). We pulled together a vast and mixed collection of primary and secondary sources to help prepare sections of the built heritage assessment. This underpinned the master planning of the building and its grounds, ensuring Berkeley Homes could progress their development plans whilst retention of the built and landscape elements of significance were guaranteed.