In the Domesday Book, Theddlethorpe is known as Tedlagestorp, believed to mean "outlying farmstead or hamlet of a man called 'Theodlac'.
Education
Theddlethorpe St Helen has a primary school.
Theddlethorpe All Saints
This lies about east of the town of Louth. Population according to the 2001 census was 212, decreasing to 165 at the 2011 Census. The parish church, dedicated to All Saints, is a Grade I listed building dating from the 12th century, with late 14th and late 17th-century alterations, and minor repairs in 1865–1866. It is built of greenstone and limestone and has a 15th-century font. At the west end is preserved a 15th-century wooden pinnacle from the tower roof. In the south aisle chapel is a brass to Sir Robert Hayton who died in 1424. Nearby is the matrix for a double brass, of which only one brass plate remains. In the chancel are two early 18th-century marble wall plaques to members of the Newcomen family. A marble monument to Charles Bertie and his wife Mary died 1727, made by Andrew Carpenter, London. All Saints was declared redundant by the Diocese of Lincoln in 1973. It is now in the care of the Churches Conservation Trust. Hall Farmhouse is a Grade II listed 16th-century red-brick house, altered about 1680 with more alterations in the late 18th and 19th centuries. Within the parish there is a medievalmoat, extant in 1963 but now only visible as cropmarks. A hearth tile bearing the arms of the Angevin family was found when excavation took place in the moated enclosure near Theddlethorpe All Saints church. The house within the moat was called Keleshall.
Theddlethorpe St Helen
This village and parish in Louth district east from Louth. had a population according to the 2001 census of 595, reducing to 525 at the 2011 Census. The parish church is a Grade II* listed building dedicated to St Helen, dating from the 14th and 15th centuries. The chancel and aisles were rebuilt by Samuel Sanders Teulon in 1866. The church is of greenstone and limestone, with a 15th-century tower, a 14th-century font, and a 19th–20th-century interior. Theddlethorpe Hall is a Grade II listed red-brick country house from the late 17th century, with early 18th–19th-century alterations. The Stable Block is also Grade II listed and dates from the 19th century.
