Officially the site of the battle is deemed by Leicestershire County Council to be in the vicinity of the town of Market Bosworth. The council engaged historian Daniel Williams to research the battle, and in 1974 his findings were used to build the Bosworth Battlefield Heritage Centre and the presentation it houses. Williams's interpretation, however, has since been questioned. Sparked by the battle's quincentenary celebration in 1985, a dispute among historians has led many to suspect the accuracy of Williams's theory. In particular, geological surveys conducted from 2003 to 2009 by the Battlefields Trust, a charitable organisation that protects and studies old English battlefields, show that the southern and eastern flanks of Ambion Hill were solid ground in the 15th century, contrary to Williams's claim that it was a large area of marshland. Landscape archaeologist Glenn Foard, leader of the survey, said the collected soil samples and finds of medieval military equipment suggest that the battle took place southwest of Ambion Hill (52°34′41″N 1°26′02″W), contrary to the popular belief that it was fought near the foot of the hill.