I haven’t found pictures of Ben and Country of the same shoot. I’ve seen them before, but never found the others. When I do you’ll definitely find them on here.
I did find a website with their promotional photo’s in high res. => http://www.bighassle.com/mumfordsons/#photo
Just click the thumbnails in “press photo’s” and you get very high resolution pictures.
Good luck with your project! I bet it’ll be really cool!
EDIT: this time with the proper links :)