c:

Keep Calm Medium  Suggested by rocamaco 


Keep Calm And Type On  Suggested by marijnkampf 
Avenir  Suggested by Niniel 

The original was hand drawn... usually the new items in that pattern use either Avenir or Gotham..

http://www.linotype.com/72/avenir-family.html
http://www.typography.com/fonts/font_overview.php?productLineID=100008&path=head

Neat. Je ne savais pas que quelqu'un avait fait une vraie police complète à partir de l'original :-)

Or use Keep Calm and Type On, which is based on the hand drawn Keep Calm and Carry On poster.