Southern have published the list of changes to the January 2015 timetable and it corresponds with this information I provided above.
More details at: http://www.southernrailway.com/southern/...uary-2015/

Some of the other Southern services will be longer (8 carriages going up to 10 carriages)

I have been corrected about the door opening of 5 carriage trains. At Canada Water one of the new sets of doors (in the rear carriage) will not open, but the other set of doors in the carriage will open.

For those changing at Whitechapel both sets of the doors in the rear carriage will not open, but you can move between carriages (if there is space to move!)

It could have been worse, and it is possible that if the Forest Hill Society had not been raising concerns every few months for the last two years, we might have lost more trains or not got more carriages.