WHAT AM I ?

Try and make the effort and try and make time
Here is a riddle by way of a rhyme 
I go around the world but stay in one place 
In England I am always proud to show the Queen's face 

Sometimes I'm important and treated as first 
When I'm inferior I'm second which is definitely the worst 
Usually found in the corner I never seem to move 
Collected by philatelists who have something to prove 

If you got the answer right I will call you a champ 
I am of course a humble postage stamp