Apologies, I should have said at the start that the 2 columns are seperate!
No need to split the text automatically... there is a distinct left and right content block on these pages:
---------------- HEADER IMAGE ----------------
...............................................
-- Nav -- --- Left header -- --- Right header ---
-- Nav -- --- Left block --- --- Right block ----
-- Nav -- --- Left block --- --- Right block ----
-- Nav -- --- Left block --- --- Right block ----
..........--- Left block --- --- Right block ----
..........--- Left block --- --- Right block ----
..........--- Left block ---
..........--- Left block ---
Now, in the admin panel, you only ever have one text area for each page - that's the part I couldn't work out.
Perhaps there is some kind of way to adapt the 'more' page splitter but using something like your suggested code, Kaf?
Or perhaps a mod to the control panel that showed two text areas when editing these kind of pages?
My main concern is that the solution must be simple and robust enough for a client to use! (Also there might need to be different header gifs at the top of either column, although clever use of sIFR might make this easier)
Thanks again for your help.