Inspired by this article:
I have tried to emulate the set up of an ipad connecting to a ubuntu box hosted by linode. Everything works fine apart from the GNU screen switching with Ctrl-A. As the author explains:
"Ctrl-X is my screen's "hot key"; it defaults to Ctrl-A, but on a wireless keyboard, that leaves Unicode characters in the terminal—I assume this is related to Apple's support for some common Emacs keybindings in iOS. It's strange, but easy enough to work around"
Easy enough, he says, but it has defeated me! I have tried bind, but can't seem to control the Ctrl keys, and am reluctant to use xmodmap as I don't want to use any graphical output. The apple wireless keyboard doesn't seem to allow any system kep map settings either.
Everything else works beautifully, so this seems like such a silly place to get stuck.