Two of the most prominent features of the Heathrow landscape were constructed in the 16th and 17th centuries. The Duke of Northumberland’s River was diverted in 1543 to increase the water supply to Isleworth Mill, and in the 17th century (during the reign of Charles I) the Longford River was constructed to improve the water supply to Hampton Court. Both these rivers were diverted as part of the Terminal 5 construction project.
During the 18th century large parts of the medieval landscape at Heathrow were enclosed by acts of Parliament. However, many of the medieval (and hence originally Bronze Age field boundaries continued in use into particularly in the western part of the site. Similarly many post medieval boundaries such as the parish boundary and Long Lane show a good fit with medieval land divisions. In the 19th and early 20th centuries Heathrow was noted as an important market gardening area. The reason for this was that the brickearth soils of the Heathrow area were very fertile, and their productivity was enhanced by vast quantities of horse manure from the huge numbers of horses required for transport in and around London. Fruit growing was also prevalent: indeed prior to the construction of the Perry Oaks sludge works in 1934, the site was occupied by an orchard.