Triangulation lines radiating from fixed points are clearly visible on this map. A pecked red line running adjacent to Lee River marks the boundary separating Essex from Hertforshire and Middlesex. Henhault Forest is shown by a stippled canopy of tree tops at the centre of the drawing. Perhaps the most interesting detail on this map is just south of the forest: a small drawing of a tree inside an enclosure marked 'Fairlop Oak'. This giant oak tree was something of a local landmark. In 1791, William Forsyth, gardener to George III, made unsuccessful attempts to halt the tree's decline. The year that this map was published, the tree was badly burnt by a fire started during a picnic. Its health steadily continued to wane until it was blown down in a gale in 1820. The inclusion of details such as the Fairlop Oak reveals the meticulous nature of the Survey, and the great attention paid to local detail.