West Sussex on Wikipedia.

Aldingbourne, St. Mary the Virgin. © David and Pat Halliday.
Angmering, St. Margaret. TQ 067 043. From a postcard in the Kevin Gordon Collection. Link.
Arundel.

Barnham, St. Mary the Virgin. A close-up of the church. From an old postcard, Bulman Collection. Previously in the Unknown section, thanks to Noel Walley for identifying this church. Link.
Billinghurst, St. Mary. From an old postcard (franked 1913), Bulman Collection. Link.
Bolney, St. Mary Magdalene. From an old postcard, Bulman Collection.
Boxgrove, St. Mary & St. Blaise. The church now serving as the parish church was originally only a part of the much larger Priory, the ruins of which are also visible in thes old postcard from the Bulman Collection. Link1. Link2.
Bramber, St. Nicholas. An inside view. Both from old postcards, Brett Jeffery's Collection. Link.
Broadwater, St. Mary. From an old postcard, Bulman Collection. A modern view. © Graeme Harvey. Link.

Chichester, the cathedral, dedicated to the Holy Trinity. From an old postcard, Bulman Collection.
Church Norton, St. Wilfrid. SZ 872 958. From an old postcard, Kevin Gordon's Collection. Link.
Clayton, St. John the Baptist. TQ 299 140. © Tony Preston. Link.
Climping, St. Mary. TQ 003 026. From the postcard collection of Kevin Gordon. Link.
Compton, St. Mary. © Juile Brutnell.
Crawley, St. Michael & All Angels (currently closed). © Peter Morgan.

East Grinstead, St. Swithun. From an old postcard (where it's spelled Swithin), franked in 1919, Bulman Collection. Link.

Ferring, St. Andrew. TQ 094 026. From a postcard in the Kevin Gordon Collection. Link.
Fittleworth, St. Mary. From an old postcard in Geoff Watt's Collection.
Forestside, Christ Church. © Julie Brutnell. Link.

Goring-by-Sea, St. Mary. TQ 111 026. From a postcard in the Kevin Gordon Collection. Link.

Hardham, St. Botulph, which Kevin says has exceptional wall paintings. TQ 039 176. © Kevin Gordon. Link.
Haywards Heath, St. Wilfred. From an old postcard, Bulman Collection. Methodist Church. 198 TQ 331 244. © Dave Westrap. Link.
Heyshott, St. James. From an old postcard in Reg Dosell's Collection. Link.
Horsham, St. John at Doomsday Green. Previously in the "Unknown" section, where it was only known as the "Forest Church" at Horsham, Janet Gimber confirmed that this is the Horsham in West Sussex. Many thanks to Janet, and to Dan Gregory for identifying it as St. John at Doomsday Green.
Horsted Keynes, St. Giles. From a 19th century engraving, courtesy of the Colin Waters Collection. Link.
Hurstierpoint.

Ifield, St. Margaret. TQ 247 376. From an old postcard, Bulman Collection.

Lindfield, All Saints. From an old postcard, Bulman Collection.
Littlehampton, St. Mary. From an old postcard, Bulman Collection.
Lyminster, St. Mary Magdalene. TQ 023 048. From the postcard collection of Kevin Gordon. Link.

Midhurst, St. Mary Magdalen and St. Denys. SU 887 215. From the postcard collection of Kevin Gordon. Link.
Milland, St. Luke. From an old postcard, Bulman Collection. Link.

Parham, St. Peter. From an old postcard (franked 1905), Bulman Collection. Link.
Petworth, St. Mary the Virgin. From an old postcard (franked 1908), Bulman Collection. The spire shown here no longer exists - see the photo on the link site. Link.

Rogate, St. Bartholomew. From an old postcard, Bulman Collection.

Selham, St. James. SU 933 207. From the postcard collection of Kevin Gordon. Link.
Selsey, the Chapel of St. Wilfrid at Church Norton. SZ 872 957. From a postcard in the Kevin Gordon Collection. Link.
Shoreham-by-Sea, St. Mary. From an old postcard, Bulman Collection. Link.
Slaugham, St. Mary. From an old postcard (where the text says Slaughan), Bulman Collection. The scanned image had to be heavily processed to get even this poor quality image. Link.
Sompting, St. Mary. Simon describes the spire as "Rhenish helm", which is confirmed in Betjeman, who adds that it is unique in England. © Simon Kidner. A view from the 1930's. Illustration from the Colin Waters Collection.
Steyning, St. Andrew. TQ 179 114. From the postcard collection of Kevin Gordon. Link.
Storrington, St. Mary. From an old postcard (franked 1905), Bulman Collection.
Sullington, St. Mary. From an old postcard, Bulman Collection. Link1. Link2.

Tangmere, St. Andrew. From an old postcard, Bulman Collection. Link.
Terwick, St. Peter. From an old postcard, Bulman Collection. Link.
Trotton, St. George. From an old postcard, Bulman Collection. Link.

Up Marden, St. Michael & All Angels. SU 795 142. © Kevin Gordon. Link.

West Dean, All Saints. 199 TV 525 996. © Dave Westrap. Link.
West Itchenor, St. Nicholas. © Juile Brutnell.
West Thorney, St. Nicholas. From an old postcard, Geoff Watt's Collection. Link1. Link2.
Wisborough Green, St. Peter ad Vincula. TQ 052 259. From a postcard in the Kevin Gordon Collection. Link.
Worth, St. Nicholas. TQ 302 362. © Rick Williams. Link.