The name of Theddlethorpe is recorded in 1086 as Telagestorp, which is believed to have derived from the Old English name Theodlac, and means the secondary settlement of Theodlac. {1} In the Domesday Book the parish combines both Theddlethorpe All Saints and Theddlethorpe St Helens, and was owned by Count Alan, Earl Hugh, Alfred of Lincoln and Sortebrand and other thanes. There is a minimum population of 15 people. {2} The lay subsidy in 1334 rated Theddlethorpe at £10 0s 10d, which is the highest in Calcewath wapentake, therefore suggesting that it was a wealthy parish. {3} In 1563, Theddlethorpe All Saints was listed with 44 families. {4} In the early 18th century the population of Theddlethorpe All Saints was 40 families. {5} The population in 1801 was 194, rising to 358 in 1871, and falling again to 231 in 1901. {6} Earthworks were observed on aerial photographs as part of the national mapping programme; these include enclosures (TF 4678 8824); (TF 4618 8828); (TF 4645 8812) and a moat {TF 4638 8787). {7} Earthworks were observed on a site visit in 2004 as part of the Lincolnshrie Coastal Grazing Marsh project. The nature of the earthworks was not recorded. (TF 4685 8831); (TF 4679 8800). {8}