Peeling Bark (and a short history lesson)

There are three of these trees outside the window of where I sit when I'm in Oxford. Everytime I walk past them I have to fight the urge to peel off a piece of bark... so far I've resisted!

While I was taking the photo, a chap asked me if I knew anything about these trees and I had to confess I knew nothing. He promptly gave me a brief history lesson - apparently during the WWII the Russians used to peel the bark off the trees, steam them and collect the oil which they produced to fill their lamps. You learn something new everyday....