Solved the problem of not being able to clear your call history. You can't.
Someone on Jolla Users asked the same question over there, he's got a year's worth of calls in his history. There's a script to run from x-terminal, but I'm not sure I wanna mess about like that at this stage. I used to run x-term scripts on the N900 but I need to learn a bit more about the Sailfish one.

I'm thinking of using mp3 files as ringtones etc as a work around.