The following text is from the original listed building designation:
TR 0446 0546 WYE HARVILLE ROAD (north side)
8/247 Spring Grove 13.10.52 and walled garden attached (formerly listed as William Wells Hall)
GV II*
House, now school. Mid C16, refaced and extended 1674 for Thomas Brett senior. Timber framed and clad and extended with red brick in Irregular English bond, with plain tiled front. Two storeys, basement and attic with parapet to hipped roof with 2 recessed dormers and stacks to left and rear right. Regular fenestration of 6 glazing bar sashes on each floor, taller on ground floor. Glazed door to right return in glazed porch with Tuscan columns, and paired glazing bar sashes on both floors over. Dovecot attached to right return. Left return with C19 cast iron and valanced verandah and conservatory. Extensive wings to rear, C18 to C20. Interior: early C17 open well stair with moulded hand rail and finial and pendant newels and large turned balustrades with identical landing balustrade. Late C17 panelled room with dado panels, rail and infill all with beaded mouldings, with pulvinated frieze. Bolection moulded wooden fireplace with 2 pilasters to overmantel. Late C18 cast iron fire grate with Neo-Classical motifs; contemporary fire place and surround and fittings (including false door (for symmetry) in ballroom. Upper room with exposed panelled framing, stop-chamfered ceiling joists and C16 stone four centred arched fireplace. The cellars contain open spring head/well. Adjoining to the south west a walled garden, some 30 metres by 50, walls of red brick about 7 feet high. The home of Thomas Brett junior, L.L.D. (1667-1743) "eminent divine and controversial writer" (Lowndes' Bibliographer's manual) and Non-Juror (bishop in 1716), meetings and services held here. Temporary home to Joseph Conrad 1919.
Listing NGR: TR0414446623 (3)

Description from record TR 04 NW 39 :
(TR04104660) Spring Grove School [NAT] (1) Spring Grove and walled garden attached. House now school. Mid 16th c, refaced and extended 1674 for Thomas Brett senior. Timber framed and clad and extended with red brick in irregular English bond, with plain tiled front. Two storeys, basement and attic with parapet to hipped roof with 2 recessed dormers and stacks to left and rear right. (Listed Grade II*) [Full archaeological description] (2)

<1> OS 1; 2500 (OS Card Reference). SKE48232.

<2> DOE (HHR) District of Ashford, 16 February 1989 (106) (OS Card Reference). SKE40470.

<3> English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.