How can I add a UTC world clock to my OSX dashboard? In the OSX dashboard, the world clock doesn't have a UTC option. Choosing London only works half of the year (the other half London is on Daylight Savings Time and is UTC+1).

I could choose Atlantic/Reykjavik, which is always on UTC, but it seems like a hack, and I'd rather have my clock display "UTC" instead of "Reykjavik".
There is already a UTC clock available.

Assuming you're on Yosemite: 


Go to your notification center  
Click Edit at the bottom  
Add the World Clock and click Done.  
Hover over the World Clock you just added, and click on the (i) icon.  
Enter UTC when it asks for City.   
That's it. You're done.