The Blackthorpe Barn was built round 1550, probably by John Drury who had just acquired the Manor of Rougham through the dissolution of the great Benedictine abbey at Bury St Edmunds in 1539.
The barn’s purpose was to be used for the threshing and storage of grain. It continued as a grain store until 1985.
The barn is timber framed. It has one side aisle and a central threshing floor between the two pairs of large doors, but its most striking feature is its vast thatched roof, over 30 metres long.
A threshing barn provided storage and working space. Unthreshed sheaves of corn were stored at one end of the building whilst threshed grain and straw were stored at the other end. In the centre was the threshing floor between the two great sets of double doors. The higher set of doors provided access for carts to drive in. There they were unloaded and were driven out empty through the lower set of doors.
Threshing was a winter task when the barn became a centre of village employment. A flail was used to separate the grain from the chaff and stalks. The thresher swung the handle of the flail over his shoulder, bringing down the swingel across the straw just below the ears. This shook the grain out of the ears without bruising it. The big doors were pinned back whilst threshing was in progress. Finally the grain was passed through a sieve. The draught from the open doors helped to carry away the chaff and dust, leaving a heap on the floor.