I called Southern to moan about the lack of carriages and they sent me a letter with a bit of good news.    At the moment we have services at 7:29, 7:51 and 8:05 with 8, 6 and 6 carriages respectively.  From May 2010 there will be trains at 7:29, 7:34, 7:46, 7:57 and 8:04 with 6, 4, 6, 6, and 6 carriages.  So in total 8 more carriages in this half hour busy period and two extra services :-)