I worked it out, but wouldn't have from that photo as it's impossible to make out. It's easier to see on
this photo of a black dial GMT someone posted on
WUS. The whole dial says "GS9F" over and over, except over the 5 o'clock marker (25 mins), where it says "25". The next "GS" is shifted along 2 places. So the sequence changes to 9F25GS, just at that point. It's particularly hard to notice because the "5" is exactly the same as an "S" and the "2" is the same thing flipped. You'd really only know it was a 25 if you were looking for it.