The Anglo-Saxon Chronicle records that the area now covered by the county of Sussex was reached by Saxon forces in 477.
 Within a few years, they controlled land along the English Channel coast as far as Pevensey.
 By the 10th century, the Kingdom of the South Saxons was fully established; its boundaries match those of the present county.
 The area was divided into smaller administrative areas called hundreds.
 Patcham and its neighbouring village of Preston were part of Preston Hundred, one of four hundreds covering present-day Brighton and Hove.
 The lowest administrative level was the parish, based around a church.
 The parish of Patcham was recorded (under the name Piceham) at the time of the Domesday survey in 1086, by which time a church existed at the centre of a small village on a spur of land near the top of the South Downs.
 The parish, which covered 4,325 acres (1,750 ha), was unusually large, and its 11th-century population of about 1,750 was one of the largest for any Sussex parish.
 William de Warenne, 1st Earl of Surrey, who held most of the land in the local hundreds, owned the manor.
 The area around the church gradually became the centre of population within the parish, and a village developed on the hillside leading up to the church, east of the modern London Road.

The Saxon church was rebuilt in the 12th and 13th centuries, and the only feature which may survive from that era is a blocked doorway.
 It was reset in the north aisle when that was built in 1898.
 The doorway has been described as "Norman or possibly earlier", "pre-[Norman] Conquest" and "could be Saxon" by various sources.
 The Victoria County History of Sussex goes further by stating it was originally in the north wall of the nave, but identifies it as 12th-century.
 The chancel arch, a "plain" structure, was inserted between the chancel and the nave in the 12th century, and the nave is of the same period.
 The 12th-century chancel was added to in the following 200 years; its Decorated Gothic windows are 14th-century.
 Similar windows were inserted in the nave at the same time.

In the 13th century, a narrow tower was built at the west end, with thin lancet windows characteristic of the era.
 Its broach spire dates from the mid-19th century.
 The tower was given substantial diagonal buttresses with sandstone quoins.
 Also at this time, the exterior underwent complete restoration with some rebuilding work.
 The only other changes made before the 19th century was the addition of a porch at the south end and some buttresses on the south wall of the nave, both in the 16th or 17th century.

Having stood for more than 600 years with little alteration, the church was completely changed by four reconstructions and restorations in a 74-year period in the 19th century.
 The last of these, in 1898, was the most substantial: it added a north aisle, much larger and taller than the rest of the building, and a vestry.
 In the early 19th century, the building had been in better structural condition than many in Sussex—a survey in 1825 by Sir Stephen Glynn of the Ecclesiological Society noted that it was "decently fitted up"—but rebuilding ancient churches was fashionable in the Victorian era, and the condition of a surviving medieval corbel suggests that the exterior walls were in poor condition.
 The three earlier periods of restoration were 1824–25, 1856 and 1880–83.
 During the third of these, a 13th-century wall painting of Christ in Judgement was discovered above the chancel arch, hidden under 30 layers of whitewash and the remains of two later paintings; it may be one of the oldest such murals in England, but it was repainted after its rediscovery.
 In 1898, at the same time as the north-side extension, the outside walls of the west, east and south sides were coated with grey cement, probably to improve their structural condition; although this has been described as "unsightly" and "kill[ing] the exterior stone dead", one historian has argued that because many medieval churches were rendered in this way, rather than having uncovered flint walls, it
The Anglo-Saxon Chronicle records that the area now covered by the county of Sussex was reached by Saxon forces in 477.  Within a few years, they controlled land along the English Channel coast as far as Pevensey.  By the 10th century, the Kingdom of the South Saxons was fully established; its boundaries match those of the present county.  The area was divided into smaller administrative areas called hundreds.  Patcham and its neighbouring village of Preston were part of Preston Hundred, one of four hundreds covering present-day Brighton and Hove.  The lowest administrative level was the parish, based around a church.  The parish of Patcham was recorded (under the name Piceham) at the time of the Domesday survey in 1086, by which time a church existed at the centre of a small village on a spur of land near the top of the South Downs.  The parish, which covered 4,325 acres (1,750 ha), was unusually large, and its 11th-century population of about 1,750 was one of the largest for any Sussex parish.  William de Warenne, 1st Earl of Surrey, who held most of the land in the local hundreds, owned the manor.  The area around the church gradually became the centre of population within the parish, and a village developed on the hillside leading up to the church, east of the modern London Road.
The Saxon church was rebuilt in the 12th and 13th centuries, and the only feature which may survive from that era is a blocked doorway.  It was reset in the north aisle when that was built in 1898.  The doorway has been described as "Norman or possibly earlier", "pre-[Norman] Conquest" and "could be Saxon" by various sources.  The Victoria County History of Sussex goes further by stating it was originally in the north wall of the nave, but identifies it as 12th-century.  The chancel arch, a "plain" structure, was inserted between the chancel and the nave in the 12th century, and the nave is of the same period.  The 12th-century chancel was added to in the following 200 years; its Decorated Gothic windows are 14th-century.  Similar windows were inserted in the nave at the same time.
In the 13th century, a narrow tower was built at the west end, with thin lancet windows characteristic of the era.  Its broach spire dates from the mid-19th century.  The tower was given substantial diagonal buttresses with sandstone quoins.  Also at this time, the exterior underwent complete restoration with some rebuilding work.  The only other changes made before the 19th century was the addition of a porch at the south end and some buttresses on the south wall of the nave, both in the 16th or 17th century.
Having stood for more than 600 years with little alteration, the church was completely changed by four reconstructions and restorations in a 74-year period in the 19th century.  The last of these, in 1898, was the most substantial: it added a north aisle, much larger and taller than the rest of the building, and a vestry.  In the early 19th century, the building had been in better structural condition than many in Sussex—a survey in 1825 by Sir Stephen Glynn of the Ecclesiological Society noted that it was "decently fitted up"—but rebuilding ancient churches was fashionable in the Victorian era, and the condition of a surviving medieval corbel suggests that the exterior walls were in poor condition.  The three earlier periods of restoration were 1824–25, 1856 and 1880–83.  During the third of these, a 13th-century wall painting of Christ in Judgement was discovered above the chancel arch, hidden under 30 layers of whitewash and the remains of two later paintings; it may be one of the oldest such murals in England, but it was repainted after its rediscovery.  In 1898, at the same time as the north-side extension, the outside walls of the west, east and south sides were coated with grey cement, probably to improve their structural condition; although this has been described as "unsightly" and "kill[ing] the exterior stone dead", one historian has argued that because many medieval churches were rendered in this way, rather than having uncovered flint walls, it 
All Saints Church, Patcham