in Keston Flint implements and pit dwellings on Keston and Hayes Commons show occupation of the area back to at least 3000 BCE, and there are
Iron Age encampments in Holwood Park and on Keston Common. In the valley below the village are the ruins of a complex of 3rd century AD
Roman tombs and mausolea () connected with the nearby 1st - 4th century AD
Roman villa excavated 1967-1992 (). Sited closer to the original Keston Court than the main village itself, Keston's small medieval church is unusual in that does not have a dedication to a saint; but built into the altar-table is the top of the 17th-century altar inlaid with a very elaborate cross and inscribed "The Keston Marke:
IN HOC SIGNO VINCES", so the parish has a distinctive symbol instead. The slavery
abolitionist William Wilberforce was a frequent visitor to the area as his close friend, the Prime Minister
William Pitt the Younger, lived at
Holwood Park. It was on top of the vale of Keston near to an oak tree that he discussed the abolition of slavery with Pitt. Only the partial dead remains of the 'Wilberforce oak' are left, but a new oak tree has been planted in its place. A stone bench, 'Wilberforce seat', commemorating the event, now marks the spot and bears the inscription from his diary "Just above a steep descent into the vale of Keston, I resolved to give notice ... in the House of Commons of my intention to bring forward the abolition of the Slave Trade." Holwood was described in Pitt's time as "a small, neat, white building; it is more simple than elegant". Pitt engaged
John Soane to enlarge the house and
Humphry Repton to improve the grounds. Soane's house burnt down, and was rebuilt in 1823-6 for John Ward in a Grecian style by
Decimus Burton. The new house was on a larger scale than Pitt's, in white brick and
Portland stone. Later owners included
Lord Chancellor Cranworth, the
Earl of Derby, and Seismograph Service Ltd. The
Keston Institute, now at
Oxford, was so named because for some years from the early 1970s it was located (as Keston College) in the former parish school on
Keston Common. Its archive is at the Keston Centre for Religion Politics and Society at
Baylor University,
Texas, so the parish's name has spread surprisingly far. There was historically a small hamlet situated to the north-east of Keston village, at the junction of Croydon Road and Westerham Road/Oakley Road; it was called Keston Mark as it lay on the border ('march' or 'mark') of Keston proper. At the 1931 census (the last before the abolition of the parish), Keston had a population of 1728. ==Keston Park==