The following text is from the original listed building designation:
BIDDENDEN SISSINGHURST ROAD 1. 5272 The Water Mill building at Hammermill Farm TQ 83 NW 3/88 II
2. Sir Richard Baker of Sissinghurst Castle established a hammer mill or forge here in the reign of Queen Elizabeth I. The former now disused mill building dates from the C18. Two storeys and attics in gable end. Red brick and grey headers. S-shaped iron ties. Half-hipped weatherboarded gable end. One window. Waterwheel.
Listing NGR: TQ8442138397

According to The Mills Archives website, the mill operated until 1914, began again in 1928 and finally ceased in 1932.

English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.