[1] The village became depopulated in the medieval era and the church fell into ruins, and the population in the isolated hilltop parish only reached 100 in the early 20th century; but rapid 20th-century development resulted in more than 6,000 people living in Hangleton in 1951 and over 9,000 in 1961.

[5] St Helen's Church was first documented in 1093 as a possession of Lewes Priory, to which it was granted by William de Warenne, 2nd Earl of Surrey.

By 1300 it was "a thriving community of approximately 200 people",[5] but during the 14th century decline set in: the population was unsustainably large, and a series of poor harvests around 1320 followed by the effects of the Black Death meant the village was almost wiped out.

Richard Bellingham, Lord of the manor at the time, incorporated stones from Lewes Priory (partly demolished in 1537) in the front of the house.

At the time of the census in 1931 the population of the parish was still only 109,[3] but during that decade residential and commercial development started apace and continued after World War II.

[9] St Helen's Church, which was "still entirely isolated" in 1929 when it was kept locked except during services, became surrounded by houses; it was reopened for regular worship in 1949,[9] having been used irregularly (sometimes as infrequently as once per year) since the mid-19th century.

[6] Housebuilding in the parish was largely complete by the end of the 1950s, although the population has continued to grow: at the 1951 census it was 6,158, rising to 9,006 in 1961[10] and an estimated 14,270 in 2013.

[11][note 1] Hangleton is popular both with families and with retired people,[12] and the percentage of residents under the age of 16 is one of the highest of any ward in the city of Brighton and Hove.

Also in the 1930s, but mostly in the 1950s, private developments of semi-detached houses and detached bungalows emerged, especially on the highest ground offering good views of the South Downs and the sea.

[17] It is a simple flint building with dressings of Caen stone, originally with a thatched roof, and is similar to other downland churches in Sussex.

[18][19] St Richard's Church, a brown-brick building designed by architects Carden and Godfrey, opened in 1961 to serve the southern part of Hangleton known as The Knoll.

[20] The Hounsom Memorial United Reformed Church was built in 1938 to the design of Brighton architect John Leopold Denman.

[33] The Grenadier pub, designed by John Leopold Denman for the Kemp Town Brewery of Brighton, opened in 1935.

[35] Tamplin's Brewery of Brighton bought land for a pub at the north end of the estate in 1948, and The Downsman opened in 1956.

To the west is Benfield Hill (TQ 261 078), a Local Nature Reserve which is famous for its glowworm displays on midsummer evenings.

On the western side of the Hill the gentle slope has longstanding populations of small blue and brown argus butterflies.

[38] To the north of the City boundary this secondary chalk grassland continues on Devil’s Dyke Farm land (TQ 260 095).

A prehistoric barrow (TQ 258 094) marked that boundary, but is now only detectable by a slight rise in the fence line as it crosses the ploughed-out mound.

In a good evening light you can see the lynchet lines of an Iron Age field system in Adder Bottom (TQ 253 101) just west of the Devil’s Dyke Farm.

There are many old barrows in the area and even the name Skeleton Hovel for the old flint barn (TQ 269 085) is thought to commemorate a prehistoric burial site unwittingly discovered during farming work.

[38] Round Hill's eastern slope (TQ 269 085) is the richest chalk grassland site in Hangleton, although it desperately needs grazing management for its many downland flowers such as field fleawort, chalk milkwort, orchids, cowslips, hairy violet, rockrose, crested hair-grass and devil’s bit scabious.

To the north of this part of Brighton and Hove downland area are the Poynings and Newtimber parishes and the impressive geography of Devil's Dyke.

[43] A bypass for Brighton and Hove, rerouting the A27 trunk road away from inner suburban areas, was first discussed in the 1920s, but the borough and county councils only voted in favour of one in 1980–81.

A route looping tightly around the northern boundary of the urban area, including the Hangleton estate, was chosen.

North of this, part of the trackbed survives as a footpath from Hangleton Way on to the Downs: the Dyke Railway Trail opened in July 1991 and can be used by horse riders, cyclists and walkers.