Archaeological investigations have identified traces of an early settlement between the church and Knebworth House.

[2][3] The most prominent feature is the 15th-century tower, surmounted by a short spire typical of the region called a "Hertfordshire spike".

The chapel is attached to the north side of the church and was rebuilt around 1710 to house three exceptionally fine monuments dedicated to members of the family.

Saints Mary and Thomas is part of the parish of Knebworth in the Archdeaconry of Hertford of the Diocese of St Albans.

[7] Media related to Saints Mary and Thomas Church, Knebworth at Wikimedia Commons