The following text is from the original listed building designation:
1. 5280 PENSHURST PENSHURST Penshurst Road (West Side)
Hammertower. Hammerfield. Culver House. Hammerfield Cottage. TQ 5244 22/842
II
2. Earlier C19 house converted and extended in 1859 by George Devey for Sir James Nasmyth, the astronomer, engineer and inventor of the steam hammer. Now divided into 4 residences. Hammerfield Cottage, at the west end, was the former observatory and workshop, the other dwellings form the original house. Entrance front of 2 storeys, 5 windows, with projecting, gabled, porch section, and octagonal tower with ogee leaded roof. Irregular building typical of Devey's style, with large-diapered brickwork and gables with ball finials. Garden front shows 5 different bargeboarded gables, mostly half timbered, with brick or plaster filling; and some tile hanging. Large mullioned and transomed windows, some of wood and some of stone. Terrace with low balustrade.
Listing NGR: TQ5231144359

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