If they're not part of the same table, you don't.
As we suspected! Thanks for the reply. We HAVE one workaround....to create a table in the usual way, rotate it by 90 degrees, and then select all the cells and make their text content (works on images too) also rotated by 90 degrees. Terribly convoluted but at least the 'column' content of the tables then flows between multiple tables / pages.