The following text is from the original listed building designation:
TQ 56 43 BIDBOROUGH PENSHURST ROAD (south side)
11/21 Mill Cottage
GV II
Small house. Probably C18 origins with later C18 or C19 rear addition. Ground floor painted brick, first floor tile-hung; peg-tile roof; brick stacks.
Plan: North-facing with 2 principal rooms at the front heated from end stacks and a later rear outshut with a gabled rear stair projection in the centre. The original arrangement may have been a 2 cell building with a parlour/kitchen at the right end, heated from a large projecting right end stack, and an unheated room at the left - the left end stack is probably a C20 addition. A straight joint indicates that the rear outshut is a later addition.
Exterior: 2 storeys. Symmetrical 3-bay front with a gabled roof and a C20 flat-roofed central porch and C20 timber casement windows. The rear elevation has a catslide roof over the outshut and a tile-hung gabled stair projection rising out of the outshut. One small rear window to the outshut, 2 small attic dormers to the rear of the ridge.
Interior: Exposed carpentry in the right hand room, there may be other features of interest.
An attractive small vernacular house.
Group value with Four Winds Windmill (q.v.).
Listing NGR: TQ5615543382

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