Is there a way to change the world clock in the sidebar to digital 24 hr time?

I'd really prefer to have 2327 for London time instead of this: Sure can't find any way to change it. Tried right clicking the clock. Tried single clicking the clock. Tried looking in Date and Time settings. I did find a clock widget that will do what I want, but it would be nice if there was some setting for the built in world clock to make it digital. I'm not in some old-timey newsroom over here!