Blackmore is a village in the Brentwood district of Essex, 7 miles SW of Chelmsford and 5 miles N of Brentwood. The church is on the southern edge of the vilage. The present church is the remnant of a mid-12thc building that originally extended further to the E, and now consists of an aisled nave and chancel in one, with 4 main bays and shorter bays at E and W. In the present liturgical arrangement the chancel is of 1 main bay with a short bay to the E, and it is separated by steps from a nave consisting of 3 main bays and a shorter W bay. There is no chancel arch. The central vessel of the nave and the W bays of the aisles are 12thc. Both W aisle bays are screened off: the N as a kitchen and the S as a childrens' play area. The remainder of the N arcade is 14thc, while the S arcade was rebuilt with brick piers in the 16thc.

At the end of the 14thc the present timber tower and spire was begun, dated by dendrochronology which gives a felling date of 1397/98. The tower is of 3 storeys, capped with a slender broach spire. Construction of the remainder is of flint rubble with flint and red brick dressings. It was restored from 1895 by Frederichk Chancellor. Romanesque features described here are the W nave doorway, now under the tower, and the W bays of the nave aisles.

Blackmore is not mentioned by name in the Domesday Survey, but is noted in the 12thc as being in the possession of a family called Sanford.The Priory of St Laurence was founded at some time in the 12thc, probably between 1152 and 1162, by members of the Sanford family. The Bishop of London, William de Sancta Maria (1199-1221) ordained vicarages at Tyburn (Middlesex), Great Hormead (Herts), Blackmore and Margaretting, all appropriated to the priory, and Henry III ordained a fair to the canons in 1232, to be held annually on the vigil, day and morrow of St Laurence. The house was dissolved in 1525.

Stylistically the W doorway and the nave arcades are similar, but the bolder and plainer forms of the doorway suggest a slightly earlier date than the more elaborate scallop capitals of the S arcade, while the trumpet scallop and waterleaf forms of the N arcade are later still, and cannot be before 1170-80. The foundation date noted above fits well with this.

The church is best known for the W tower, described by Pevsner as 'one of the most impressive, if not the most impressive, of all timber towers of England.'