The full 1841 Census of Tetworth Parish is available as fiche set C80.
The full 1851 Census of Tetworth Parish is available as fiche set C30.
The full 1891 Census of Tetworth Parish is available as fiche set C13.
A surname index of the 1881 Census of the St. Neots Registration District, in which Tetworth was enumerated (RG11/1611, Folios 130a - 134b), and which took place on 3rd April 1881, is available as fiche set C5.
The church of St. Mary consists of a chancel, nave, north aisle, south aisle, west tower and south porch. The walls are of stone rubble with stone and clunch dressings, but those of the tower are mostly of ironstone. The roofs are covered with tiles, slates and lead.
The church is mentioned in the Domesday survey of 1086, but this early church was rebuilt in the middle of the 12th century, as a chancel and an aisled nave, the greater part of which still exists. At the end of the 14th century, the tower, south porch and clearstory were built, and about 100 years later, the chancel arch was rebuilt.
A general restoration took place in 1865 when the north wall of the north aisle and the south-east corner of the south aisle were rebuilt.
The Huntingdonshire Marriage Indexes include marriages from this parish. These are, at present, issued in alphabetical listings in series: 1601-1700, and 1701-1754, and are available from the Huntingdonshire FHS.