I used to have a permanent indentation near the base of my left index finger where the flute rested.

http://www.thegalwaynetwork.com/notes/hold.htm

The first picture shows you James Galway's callus at the same point, and the third picture shows you that indentation and the ones on his fingertips. I never played an open-hole flute for any length of time so I don't know whether I would have gotten similar fingertip markings or he presses down particularly hard, but the index finger indentation looks pretty similar, modulo general hand shape.