Illston on the Hill is a small village in the Harborough district of SE Leicestershire, 7 miles N of Market Harborough. Illston is unusually a dead-end village, and the church is in the centre. St Michael's consists of a W tower, a clerestoreyed nave with S aisle and S porch, and a chancel. The fabric is largely of the late-13thc or later. It is built of coursed rubble stone and was restored by H. Goddard and Son in 1866-67. Only the font is Romanesque, and must be from an earlier building.

In 1086, most of Illston on the Hill was held by Hugh de Grandmesnil; 9 carucates of ploughland less one virgate. His holding also included 20 acres of meadow. The remainder was held by Ingald, part of it in alms from the king (2 carucates and 1 virgate) and the rest (from Robert de Bucy (half a carucate). In 1231 an estate at Illston was granted to Creake Priory (later abbey) in Norfolk, and that house held most of Illston until 1507, when all the monks died in an epidemic and its lands reverted to the crown.

The church was in 1220 a chapel under the joint ownership of Nosely and Carlton Curlieu churches, both nearby.

The font is of rustic workmanship but curiously sophisticated form, and is decidedly unusual. The base appears to be original, and the 3 heads are differentiated. The curious form of the base perhaps also carries some iconographic weight. The damaged state of the font combined with the fact that it is considerably older than any of the fabric of the church suggests that it may have been exposed to the elements for some time. Pevsner is vague about the date, suggesting 'possibly C12 or c. 1200'. The list description opts for a 12thc date and VCH simply says that it may have belonged to an earlier building. A date in the mid-12thc or slightly earlier is suggested here.