The Old College is a rare survival of a medieval collegiate grammar school and one of the earliest brick buildings in England.
It is also important as part of Ralph, Lord Cromwell’s great building programme at Tattershall. It is a scheduled monument and a Grade II* listed building and is protected by government legislation.
The building probably owes its survival to the fact that it continued in use into the early 20th century. However, its use changed over time, and these changes necessitated alterations to its fabric. Major alterations were made in the late 18th century when the building was converted to a maltings. Some of these are still visible today and are considered important as evidence of the building’s history.