A magnetometry survey was conducted to inform the conservation and management of Tattershall Castle. The survey recorded the remains of probable former structures and enclosures likely associated with the former Tattershall College, along with the nearby remains of a previously identified later causeway. The possible course of the outer castle moat was also recorded in the area known as the Tiltyard, along with a number of probable former fishponds in the meadowland to the south-east of the castle. {1}