Former chapels of ease in outlying hamlets have closed, and the church now serves a large rural area in the centre of Sussex.

From his base at the episcopal see of Selsey, which he founded, the 7th-century bishop Wilfrid converted many of the pagan inhabitants of the Kingdom of the South Saxons (present-day Sussex) to Christianity.

[2] It was rebuilt in about 1250, when the Bishop of Chichester Richard de la Wych (later canonised) made an agreement with Lewes Priory to endow a vicarage and improve the church.

[1][7] He appointed his chaplain Walter de Warnecamp as the church's first parish priest, and put him in charge of the enlargement.

The south wall of the Norman chapel was demolished and a three-bay aisle was built in its place, reached through three archways with round columns.

[10] Several windows with flat headers and ogee-arched lights also date from this era,[10][11] and the slim, tall spire is believed to be contemporary as well.

[2][8][10][12][13] The external roofline was changed in the late 15th century: the walls of the aisles were built up, and the roof was brought down in a single sweep from the ridge to the eaves.

This work, which had the effect of blocking the quatrefoil windows in the clerestory, was done in conjunction with the installation of a wagon vault ceiling with tie-beams and spandrels.

[13] Further enlargement came in the following century, reflecting Cuckfield's steadily increasing prosperity: a chapel was added at the northeast corner for the use of the locally important Sergison family.

[3][10] The English Reformation of the 16th century, through which Protestantism became established and Catholic-style worship and practices were banished, affected Holy Trinity Church in the same ways as other churches: statues, icons and paintings were removed or destroyed, the internal layout was simplified, Holy Communion rituals were altered, English was used instead of Latin, and objects ranging from hymn-books to the altar had to be stripped out and destroyed in public—often by being burnt.

Dr James Marsh, appointed vicar of Cuckfield in 1638, had Royalist sympathies and became one of the thousands of clergymen who were removed from their parishes and had their possessions sequestered.

[4] The Restoration of the Monarchy in 1660 ended this turbulent period, and more structural work was soon carried out on the church: the spire was shingled and a clock was installed in the tower in 1667.

[18] Some minor work had also been carried out in the 1630s: altar rails were installed in 1637, the building was painted, a gallery was added inside and the vicar hung the church's first ring of bells.

[22] The rapidly growing town only came into existence after Cuckfield villagers and the church authorities refused to allow the London to Brighton railway line to be built through the village: its planned alignment took it past the east side of the churchyard, but the London and Brighton Railway company moved it 1.5 miles (2.4 km) to the east across the unpopulated heathland after which residents gave their approval.

The same parishioner presented a new organ in 1842, which was well received by all and immediately changed the character of worship at the church, which had previously relied on a choir for musical accompaniment.

[21] In 1846, a baptistery was formed in one end of the south aisle, some of the windows were reglazed (some with stained glass), a tiled floor was laid and new oak pews were installed.

The comprehensive reconfiguration and rebuilding carried out by him and his pupil Charles Eamer Kempe has given the building a largely Victorian appearance.

[3][27] Changes were made in all parts of the church: Bodley installed marble steps and railings in the chancel, raised the floor height in the chancel, installed a new reredos of alabaster (no longer in place), changed the 17th-century triple-deck timber pulpit[3] for a new, smaller version of stone and wood, put in new choir stalls, removed the galleries, opened out one of the arcades in the south aisle which had been partitioned previously, renewed all the floors, lowered the floor in the tower to bring it in line with the rest of the church, re-roofed the south aisle and installed three new windows and removed a chandelier, which was donated to a church in Oxford.

[27] Charles Eamer Kempe's association with the church began in 1865, when Bodley commissioned him to paint the wagon vault ceiling, which was still in its unadorned 15th-century state.

[12][28][29][30][31] He also designed and installed several stained glass windows between 1875 and 1887, for example in the north aisle and west wall,[12][29] and rebuilt the south porch in 1883 using most of the original stonework.

A memorial tablet of white marble, listing the names of all Cuckfield residents killed in the First World War, was installed inside the church in 1922.

[33] In the same year, repairs were found to be needed to several parts of the building and its fixtures; the Diocese of Chichester provided funds to supplement the offertory, and work started immediately.

One was designed by Charles Eamer Kempe in either 1887[3] or 1893;[44] the structure is entirely of timber, supporting a "pagoda-shaped" of Horsham stone tiles topped with an iron cross.

[45] Enlargement took place in 1855 to accommodate burials from the growing railway town of Haywards Heath, which at that time was still in Holy Trinity's parish.

[9] The church, standing on the south edge of Cuckfield off the High Street and with long views across the Weald,[7] is "the focal point of the village",[49] despite the site being the lowest land in the area (305 feet (93 m) above sea level).

This was enlarged with a proper chancel in 1883,[51] and on 10 December 1909 it reopened in a new, brick-built form as St John's Chapel after being rebuilt and rededicated as a memorial to a local resident.

[54][55] Thoughts of closing the church first arose in 1998, when finding enough clergy and laypeople to run it effectively started to become very difficult, and in January 1999 the proposal was put to worshipers and local residents.