Kilygarvan, "the wood of the rough field" is a a praish half way up the west coast of Lough Swilly. The Church is in Rathmullan, where there are the remains of an ancient priory. At the survey in 1622, the church was considered to be in such bad repair , that it would be better to worship in the old priory. By 1729, the church which had been consecrated in 1706, was in good repair. Another church was built in 1814.
The present church dates from 1887, when the chancel, organ chamber and vestry were added to the building of 1814. At the west end is a tower, with a window on either side, and the entrance to the porch in the west end. Inside is a gallery, under which to the left is the baptistery.
In the north wall, at the west end, are two small square windows, one below the other. There is also a large window with three lights, commemorating Thomas Batt of Rathmullan House who died in 1857.
It contains the Batt family crests. In the south wall are three windows, each with two lights. The first two are of clear lattice glass. The third window depicts Jesus with Martha, her sister Mary, and Lazarus and is in memory of Letitia, daughter of the Rev. and Mrs C. Gayer. There is an opaque glass window in the south sanctuary wall.
The east window, dated 1883, is in memory of Elizabeth Otway, daughter of Thomas Batt, who died in 1878. The four lights depict, Jesus walking on the water, the miraculous draught of fishes, the woman caught in adultery, and the raising of Lazarus.
The prayer desk was presented by David Kelly in memory of his sons. The lectern is nicely carved. The pulpit is in memory of the Rev. Henry Stewart Cochrane, Rector of Killygarvan, 1835-1880. The organ and the altar, which is dated 1936, are in memory of the Rev. William Battersby Lloyd, Rector 1883-1907.
Three important families left their mark on the parish in the 18th and 19th centuries, and their monuments are in the church. One of these was the Knox family of Prehen, Lonodnderry, descendents of Andrew Know, Bishop of Raphoe 1611-1633. On the north wall are a roll of honour and a monument to those who fell in the Great War. Next is the monument of Andrew Know of Prehen, M.P. for Donegal who died in 1774, and his daughter Mariana who died in 1761. In the south wall, Dominick, son of Andrew Knox, who died in 1851, is commemorated .
The Batt family of Purdysburn, Belfast arrived in Rathmullan. They had come up through County Wexford in the 18th century. They were bankers, founders of the Belfast Bank. Thomas Batt bought the Knox properties around Rathmullan, and rebuilt Rathmullan House, now a hotel. The east window, as has been said, commemorates his daughter.
The Montgomery family was prominent in military life in the 19th and early 20th centuries. Their residence was Fort Royal, also now a hotel. On the east wall of the nave , to the right of the sanctuary, and adjacent to them on the south wall, are several brass plaques to the family. On one, General George Samuel Montgomery who died in 1898, and his wife, Letitia, who died in 1894 are commemorated. His son, Major T. R. A. G. Montgomery who died in 1922, is commemorated on another brass plaque, and another son, Col. C. A. S. Montgomery is also commemorated. Brigadier Harold Matthews, C.B.E who died in 1947, and his wife Sybil, daughter of J. H. Jellet are commemorated on two plaques. J. H. Jellet was in the Royal Artillery. He died at Fort Royal in 1938, and is commemorated, as is his daughter, Salisbury Mable who died in 1950.
There are two brasses to Brigadier General Arthur B. Stopford, Royal Artillery, who died in 1902, and his wife Evelyn, who died at Fort Royal in 1949. In the south wall is a monument to Gardiner Trouter who took part in the Crimean War, and who died at Sevastopol in 1851.
In the north wall of the sanctuary is a monument dated 1887 to Henry S. Irwin, who died in 1823 aged eight years, and in the east wall of the nave, a brass memorial commemorates the Rev. Andrew Noblett, Rector of Killygarvan, 1924-1937, who died in 1948.