Sessions clock adjustment?

I have acquired two Sessions mantel clocks. The movements look very similar. One clock has the F and S above the adjustment hole and the other has it below the hole. In each case the F is toward the left side but this indication is ambiguous. I am unclear whether the adjustment key is supposed to turn clockwise or anticlockwise to speed the clock up. Presumably it is the same for both clocks. Any advice ?

Julian Thomas
May 2015