The earliest possible site in Barton Hartshorn is a Roman road that was seen on an aerial photograph running towards Tingewick. In the Saxon and medieval period Barton Hartshorn was part of Bernwood Forest. Bernwood had been a hunting forest from the time of Edward the Confessor. It grew to its largest extent under Henry II. The whole area was not covered by woods; in the medieval period a forest was a place where deer roamed for hunting and so included open land, villages and fields. All those who lived in the forest were not allowed to hunt or even gather wood without a special licence from the king. Bernwood Forest was finally disafforested in the reign of James I in 1635, although it had been shrinking in size since the time of King John (1199-1216). An ancient wild boar was found in Boar’s Pond, a medieval mound that was levelled in the 19th century. It was said to be that of a legendary wild boar killed by one of the ancestors of the Chetwode family. The mound can be seen as a soilmark on aerial photographs. A 10th century document records the 'Halgan Oec', a named tree, as part of the boundary with Oxfordshire.
Barton is recorded in Domesday and is first recorded as Barton Hartshorn in a 15th century document. The village was bigger in the medieval period and house platforms and hollow-ways remain as earthworks around the village, as does ridge-and-furrow, the remains of medieval farming techniques. The only surviving medieval building is St James’ church, which dates back to the 13th century and was enlarged in the 19th.
Other listed buildings in the parish date to the 16th to 19th centuries. The 19th century also saw some industrial activity with a gravel pit dug north of Orchard Cottages. The railway was the Great Central, which was opened in 1899. Though now closed, cuttings and structures can still be seen along its length. There is a registered garden at the manor house, dating from the early 20th century. Part of Finmere Second World War airfield also protrudes into Barton Hartshorn parish.