Stands on the south side of the village and is built of flint with stone dressings. The roofs of the chancel, nave and north porch are tiled and the others roofs are covered with lead. There are indications that there was an 12th century nave which was lengthened towards the west circa 1270 when the south aisle was built. The north aisle was added in 1340 at the same time the chancel was rebuilt with a vestry on the north side which has since been destroyed, the clearstory may have been added about the same time. There have been various other alterations and additions since but in 1867 the whole church was restored and all the stonework re-tooled.
The fittings include a 17th century carved chair in the chancel, a chest at the west end of the north aisle, with a panelled front, plain lid and three locks, probably late 17th century. There is an Easter Sepulchre in the north wall of the chancel, it is 2 ft 2 inches wide and 10 inches deep, with trefoiled ogee head, crocketed label and carved finial, pilasters at the sides with corbels carved as heads of knights in mail coifs, late 14th century and has been much restored.
The font is modern. At the east end of the south aisle is the bowl from the original font, with the top worn or broken away, but the ornament indicates shallow arcading and below this is a series of circular flowers of sunk shell pattern, 12th century, much defaced, and had been used as a flower pot in the garden, and was restored to the church in the 19th century.
In the chancel there is a 14th century piscina, much scraped and partly restored, and in the south aisle there is another piscina with trefoiled two-centred head also of the 14th century.
In the chancel there are three sedilia in line with the piscina, these are also of the 14th century and have been much restored.
The Church of St Leonard, stands about 3 3/4 miles southeast by south of the parish church of Aston Clinton. The original chapel is believed to have been built on the site of an ancient hermitage or cell belonging to Missenden Abbey, and founded circa 1278 when Richard Gravesend, Bishop of Lincoln and Archdeacon of Oxford, performed his visitation and granted to William de Clinton, patron of the church of Eston (Aston Clinton), a chapel within that parish. It was called "The Chapel of St Leonard of Blakemore".
After the dissolution of the Monasteries, the chapel seems to have been disregarded, until Queen Elizabeth, in 1586, granted its site to Edward Wymarke for services. At the time it was in tenure of Silvester Baldwin who held other lands in the same parish which the queen had granted to Sir Edward Stanley, Knight, and his heirs. In 1587 it is recorded that Queen Elizabeth granted "the decayed Free Chapel of St Leonard, a tenement called Chapel Farm, and all lands thereunto belonging in Aston Clinton and Wendover" to "William Tipper and Robert Daw, esqs."
Much of the present church is thought to have built in the 15th century, however, the piscina and sedile are 14th century and appear to be of re-used material possibly from the earlier building. The walls of the church are covered with cement and the roofs tiled. The west end of the nave which supports the Bell Cot is a later edition. Restoration was done to the church in the 17th century. The south porch and small north porch are modern.
The Bell Cot is square with thin walls, possibly timber framed, but now covered with cement and topped by a tall pyramid shaped roof, with a weathercock at the pinnacle. There is one bell which is inaccessible, it was made in 1702 by Chandler of Drayton Parslow..
The piscina in the chancel, with cinquefoiled two centered head, label, having head stop on the east side and carried over the sedile on the west side, octofoil basin, partly cut away in front, probably 14th century, the head modern. The sedile next to the piscina with cinquefoiled two centered head and label, also probably 14th century, the head and west jamb modern; the label continues towards the west apparently for a second sedile.
There are two large commemorative memorials to the Wood family, one of which has a fine marble bust of General Cornelius Wood who died in 1712.
The sanctuary 'Fletcher' memorial window designed in 1918 by Gregory Strachan replaced an earlier stained glass window.