East Sussex on Wikipedia.

Alciston. The dedication is lost. From an old postcard in Geoff Watt's Collection. Link.
Alfriston, St. Andrew. From an old postcard, Bulman Collection. A modern view. © Graeme Wall. Link.

Battle.
Beckley, All Saints. TQ 843 237. From a postcard in the Kevin Gordon Collection. Link.
Beddingham, St. Andrew. TQ 445 079. © Kevin Gordon. Link.
Bexhill, St. Mary Magdalene. From an old postcard, Bulman Collection. The card was posted in 1957, but is evidently much older.
Brightling, St. Thomas a Becket. The pyramid is the tomb of the one-time MP "Mad Jack" Fuller. TQ 683 210. From a postcard in the Kevin Gordon Collection. Link.
Brighton.
Buxted, St. Margaret the Queen. From an old postcard in Peter Wenham's Collection. A modern view, © Peter Wenham. Link.

Chailey, Free Church. © Geoff Watt.
Crowhurst, St. George. From an old postcard, Steve Bulman's Collection. Link1. Link2.

Dallington, St. Giles. Grade II* listed - link. Former Methodist Chapel - has been disused for several decades. Both © Chris Emms (2011).
Denton, St. Leonard. Interior view. TQ 454 025. Both © Kevin Gordon. Link.

Eastbourne.

Fletching, St. Andrew and St. Mary the Virgin. © Chris Emms (2011). Link. Grade I listed - link. 
Folkington, St. Peter. TQ 559 038. © Kevin Gordon.
Framfield, St. Thomas à Becket. © Peter Wenham. Link.
Frant, from an old postcard, Steve Bulman's Collection.
Friston, St. Mary the Virgin. TV 552 982. Kevin says the church is now surrounded by trees. From a postcard in the Kevin Gordon Collection. Link.

Glynde, St. Mary the Virgin. TQ 457 093. © Kevin Gordon. Link.
Groombridge, St. Thomas the Apostle. Link. St. John. Both from an old postcards, Geoff Watt's Collection.

Hampden Park, St. Mary. Link. St. Joachim (R.C.). Both © Graeme Harvey.
Hastings.
Herstmonceux, All Saints. TQ 643 102. © Kevin Gordon. Link.
Hooe, St. Oswald. Another view. The sun-dial. All © Steve Bulman (2009). Link.
Hove.

Icklesham, St. Nicholas. © Geoff Watt. Link.
Iford, St. Nicholas. TQ 408 074. From a postcard in the Kevin Gordon Collection. Link.

Jevington, St. Andrew. From an old postcard (franked 1904) in Steve Bulman's Collection. Link.

Lewes.
Litlington (O), St. Michael the Archangel. Curiously, Pevsner fails to give the dedication. 199 TQ 523 019. © Dave Westrap. An old postcard view, from Reg Dosell's Collection. Another view, two interior view - 1, 2 - and the font, all © Steve Bulman (2009). Link.
Lullington, Church of the Good Shepherd. One of the smallest churches in Britain, though only the remaining portion of a once larger church. From an old postcard, Steve Bulman's Collection. Link.

Maresfield, St. Bartholomew. From an old postcard, Bulman Collection. Link.
Mayfield, St. Dunstan (O). From an old postcard, Steve Bulman's Collection. Interior view, and an iron tomb slab - note the reversed "7" and the "N" towards the top. © Judith Anderson (2009). Baptist Chapel. © Judith Anderson (2009). Colkins Mill Church (previously Congregational). TQ 583 269. © Judith Anderson (2009). Link.

Newhaven, St. Michael. TQ 442 011. From a postcard in the Kevin Gordon Collection. Link. Christ Church, which stood on South Road, was demolished in 1969. From a photo in the Kevin Gordon Collection.
Newick, St. Mary. From an old postcard (franked 1911) in Steve Bulman's Collection. Link.
Northiam, St. Mary. Another view. TQ 830 245. Link. Northiam Unitarian Chapel, identified by Janet Gimber. TQ 823 250. All © Steve Bulman (2009).

Offham, St. Peter. TQ 401 122. From a postcard in the Kevin Gordon Collection. Link.

Peasmarsh, St. Peter and St. Paul. © Bill McKenzie. Former chapel (now a private residence). © Geoff Watt. Janet Gimber advises that this was Wesleyan Methodist.
Pevensey, St. Nicholas. From an old postcard in Steve Bulman's Collection. Another old postcard view, this one from Reg Dosell's Collection. A modern view, © Stuart Mackrell. Grade I listed - link.
Pett, St. Mary and St. Peter. From an old postcard, in Reg Dosell's Collection. Link.
Polegate, from an old postcard, Steve Bulman's Collection. U.R.C., formerly the Congregational Church. TQ 584  050. From a postcard in the Kevin Gordon Collection (posted 1907). Link.

Ringmer, St. Mary the Virgin. TQ 445 126. © Kevin Gordon. Link.
Ripe, St. Andrew. © Chris Emms (2011).
Robertsbridge, U.R.C., originally Congregational (1881), which Pevsner records, rather unkindly, as "truly horrible". Bethel Chapel (1842). Both © Steve Bulman (2009).
Rotherfield, St. Denys. From an old postcard (ca. 1910), Brett Jeffrey's Collection. Link.
Rottingdean, St. Margaret. From an old postcard (franked 1904), Steve Bulman's Collection.
Rye.
Rye Harbour, Church of the Holy Spirit (CoE). Memorial to Lifeboat men. TQ 937 190. Both © Dave Westrap. Another view. © Steve Bulman (2009). An old postcard view, from Kevin Gordon's Collection. Link. Church Mission Room. Approx. TQ 940 190. © Steve Bulman (2009).

St. Leonards-on-Sea, Christ Church. From an old postcard (franked 1906), Steve Bulman's Collection. St. Ethelburga, built in 1929. From a postcard in the Kevin Gordon Collection. Link.
Salehurst, St. Mary the Virgin. Another view. Both © Steve Bulman (2009). Link.
Seaford.
Sedlescombe, St. John the Baptist (O). Interior view, and an angel. TQ 776 188. All © Steve Bulman (2009). Link.
Southease, dedication lost. TQ 421 064. From a postcard in Kevin Gordon's Collection. A modern view, and an interior view, both © Chris Emms (2011). Grade I listed - link. Link2.
Stanmer, no dedication (CoE). © Bernard Hylands. Link.
Staplecross, St. Mark. © Steve Bulman (2009). Link.

Tarring Neville, St. Mary TQ 444 038. © Kevin Gordon. An old postcard view (card franked 1905), from Steve Bulman's Collection.
Ticehurst, St. Mary the Virgin. From an old postcard, Steve Bulman's Collection. Link.

Upper Dicker, Holy Trinity. TQ 553 099. From a postcard in the Kevin Gordon Collection. Compare with this modern view (and another) - note that the triangular hat on the bell cote has gone. © Steve Bulman (2009).

Wadhurst, St. Peter and St. Paul. From an old postcard, Geoff Watt's Collection.
Waldron, All Saints. From an old postcard, Steve Bulman's Collection. Another view, from a postcard in the Kevin Gordon Collection. Kevin advises that this church is also known as All Hallows. TQ 549 193.
Wartling, St. Mary Magdalene. TQ 658 092. From a postcard in the Kevin Gordon Collection. Link.
West Dean, All Saints. 199 TV 525 996. © Dave Westrap. Link.
Westham, St. Mary, situated beneath the walls of Pevensey Castle. TQ 642 046. From a postcard in the Kevin Gordon Collection, and another from Reg Dosell's Collection. Link.
Whatlington, St. Mary Magdalene. Another view. Both © Steve Bulman (2009). Link.
Willingdon, St. Mary the Virgin. From an old postcard in Steve Bulman's Collection. Link.
Winchelsea, St. Thomas the Martyr. From an old postcard, Steve Bulman's Collection. Three modern views- 1, 2, 3 - all © Steve Bulman (2009). Link. Wesley's Chapel (Methodist). Winchelsea was the last place that John Wesley delivered a sermon, beneath a large ash tree, beside the old church. © Steve Bulman (2009).
Winchelsea Beach, St. Richard of Chichester (1935). Another view. The "Rhenish Helm" roof is unusual - see also Sompting in West Sussex. Both © Steve Bulman (2009).
Withyham, St. Michael and All Angels. From an old postcard, Steve Bulman's Collection. Link.
Wych Cross. At first glance this church looks a bit like Whippingham on the Isle of Wight, but it isn't. Diana Bond had asked for  help in identifying it. Paul Smith has advised that Wych Cross Church, which was dedicated to St. Richard de Wych, although never consecrated, was built in 1866 and demolished in 1975.