Description from record TQ 73 NE 7 :
TQ 779359. Windmill. Kent's most famous mill and the tallest mill in the country. This octagonal smock mill on a very high brick base rises to 72ft (22m) to the top of the cap. Standing on a hill in the centre of the town, it is a landmark for miles. It was built by Henry Dobell in 1814, as a stone tablet over the door records, and another stone tablet records that John Russell was miller from 1918 to 1956. When built it has common sails and no tantail but these were replaced by patent sails and a fantail added in 1840. Standby power was provided by a steam engine in 1863, a gas engine in 1919 andan electric motor in 1954. The mill is in full working order, with 2 of the original 3 pairs of stones. The present sweeps are unusual, having the steel stock and pair of whips in one piece, which is a Dutch design, but with English patent sails whereas the Dutch ones would be plain sails. Only animal feed is produced. The mill is open to the public (see illustration card). (1) Henry Dobell. Grade I (See list for further details). (2) Additional bibliography. (3-8)

The following text is from the original listed building designation:
CRANBROOK THE HILL TQ 7735 NE (north-east side) 12/196 Cranbrook or Union 9.6.52 Windmill (formerly listed as The Windmill) GV I
Smock Mill. 1814, by millwright James Humphrey; Henry Dobell miller. Painted brick base with timeber framed and weatherboarded structure above and timber framed and weatherboarded boat-shaped cap. Wooden sweeps and fantail. Four storey base and four storey upper structure. Scattered fenestration in both upper and lower parts with various entrances and granary doors. Encircling platform above base of wood on iron braces with iron railing. Machinery intact and in working order; still in use as a mill, though more often milling by electricity than by wind-power.
Listing NGR: TQ7790635946 (9)

Archive material (10)

<1> Ind Arch of SE Eng 1978 33-35 photo (AJ Haselfoot) (OS Card Reference). SKE44223.

<2> DOE(HHR) Dist of Tunbridge Wells 1986 68 (OS Card Reference). SKE41099.

<3> The NT Guide to Our Industrial Past 1983 22 207 (A Burton) (OS Card Reference). SKE50448.

<4> Ind Arch Sites of Brit 1977 45 (A Burton) (OS Card Reference). SKE44272.

<5> The Arch of the Indus Rev 1974 92 (B Bracegirdle) (OS Card Reference). SKE50072.

<6> Windmills of Eng 1976 98-9 (RJ Brown) (OS Card Reference). SKE51365.

<7> Windmills in Kent 1979 7 (BJ and JM Turpin) (OS Card Reference). SKE51352.

<8> The Windmills of Kent 1979 36-9 (J West) (OS Card Reference). SKE50546.

<9> English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.

<10> Historic England, Archive material associated with Union Windmill in Cranbrook, Listed Building (Archive). SKE53926.