[ALUG] Anyone know how to change user on Raspberry Pi GUI login?

As per the subject. I have a Raspberry Pi with the latest raspbian installed. I've told it to run the GUI at boot. I want to change the user that it boots into, i.e. I don't want it to boot into the default user 'pi'. How does one do this? Google searching brought up all sorts of things about changing the pi login but not what I wanted to do. -- Chris Green