Alternatively you could use the Keep Calm and Type On font from
www.keepcalmstudio.com. It has both the crown and the upside down crown included. I've specifically designed it to match the font from the original Keep Calm poster.

Avenir Next is found on Mac computers. When bolded, it is the Keep Calm font.
Gill Sans is the Helvetica of Great Britian, and I've always just assumed it was set in Gill. After doing some reserach, though, it seems that the "Keep Calm" font is the best choice since the first posters were hand-lettered. Apart from the terminations on the C, Gill just feeeeels right. Maybe because it's so English...
Suggested font: Gill Sans
All times are CET. The time is now 09:07