The first record of a church at Reche was the founding in 1378, by Sir John Peksbridge, of a perpetual chantry chapel dedicated to St. Etheldreda the Virgin, foundress and first Abbess of Ely probably on the site of an earlier consecrated building, there being a Guild dedicated to St. John formerly in this place.

The first chaplain was Robert Prior. Little is known of his successors, but in 1457, "Robert Sparkes, a priest of this place, was made at Cambridge publicly to do penance and retract his errors of heresy." At the Dissolution of Chantries, there were 45 acres of land attached to the chapel, an endowment which was then appropriated to the Crown. The building being mainly constructed of clunch a hardened form of local chalk which also provided the material for the Lady Chapel at Ely Cathedral was of negligible demolition value and the fabric was therefore left to decay.

By 1768 there remained but a roofless sanctuary and portions of two side aisles. Only the eastern wall and window of the chancel still stand, now scheduled, in these more enlightened days, as a building of historic interest and worthy of preservation. Following the Reformation, Reach was without a church until the 19th Century, the cure of souls being divided between the Parish of Swaffham Prior and that of Burwell. In 1861, largely by the efforts of the Rev. Thos. Preston, Vicar of Swaffham Prior to whose Parish, with the levelling out of the lower end of the Dyke to form the village green, Reach had been united in the previous century and the present building was erected on the site of the earlier foundation.

A copy of the Illustrated London News "of this time, preserved in the church, shows its highly original, if somewhat curious, frontal appearance and gives its architect's name as Ch. Foster Hayward, its builder, William Bell of Cambridge, and its cost as £300. Known as Holy Trinity Church, it was designed to fulfil the dual function of day-school and church to serve as a chapel-of-ease to Swaffham Prior. It continued in this double duty until terminated in 1909 by the erection of a separate school building. This latter event prompted the cryptic remarks in the church records by the priest-in-charge, Church clear of Day-school. "Thank God!"

The church was badly damaged by lightning in 1958, which gave an opportunity for a complete restoration of the fabric and the redesign of the internal layout and fittings. A medallion in the upper section of the west window commemorates the completion of this work. As no positive evidence existed that the present building had been formally dedicated, the restored church with its two altars was dedicated in its centenary year to St. Etheldreda and the Holy Trinity, by the Lord Bishop of Ely.

Of cruciform design, with an apsidal sanctuary, the church is constructed of brick and clunch. It is sited some 25 feet north-west of the older chapel, a charming view of whose remains can be seen through the small rectangular window in the south transept. The modern altar, credence table and altar rails, designed by O. J.Bourne, A.R.I.B.A., were made locally, the former a gift of one of the Wardens. The font, a delightful 18th Century marble bowl designed in the Italian manner, standing on a freestone base, comes from the derelict church of St. Cyriac and St. Julitta, the disused of the two churches at Swaffham Prior. From the same source comes the oak lectern, as also the vestry screen and interior porch, constructed during the recent rehabilitation from the panelling of the old box pews. The wrought iron candelabra was designed and made in the village and presented with the electric lighting installation as a gift of work. A further gift from the same donor, the pipe organ of 25 stops above the west end porch, has an 18th Century Baroque specification and is played by electric action from a detached console of two manuals and pedal located in the south transept. The finely carved oak processional cross, a recent gift from the Vicar and Wardens of St. Mary, Burwell, is worth attention.

St. Etheldreda's side chapel in the north transept has for its altar the table and credence bracket originally used in the sanctuary; the silver table ornaments are the gifts of one of the parishioners.

The church plate consists of a silver chalice, paten and flagon purchased in 1900. The single bell and clock (by J. W. Benson, London) are both dated 1860. Independent registers have been kept since 1901.