The label "champion" is a complex one to wear and one which I've been a bit cautious about recommending anyone use. In the UK, it's been common to identify that enthusiastic doctor or nurse, label them the champion for the work and then expect them to get on and lead the changes. Sometimes this works, and sometimes it doesn't.
There's a really interesting paper published (by Hendy & Barlow, Imperial College, London) which examines the role of the champion and their effectiveness in one program in the UK. I like this research because it is lengthy (three years is a long time) and ethnographic. Their bottom line, it seems, is that it's good to be a champion in your own patch, but as soon as you're expected to deliver your champion role outside your regular context, then the effectiveness drops off. This is instinctively logical but all the same it's good to see some research on the topic.
Soc Sci Med. 2012 Feb;74(3):348-55. Epub 2011 Mar 1.
The role of the organizational champion in achieving health system change.