So the problem is that I've installed (g)Vim and the arrow keys are moving around rather than going through command history.
It's a little complicated by the fact that there was an old version of vim installed by a different user (I've just inherited someone else's dev machine at a new job). I'm running on windows and have just deleted the vimrc under program files.
What setting has changed this behaviour and how do I change it back to normal mode?