First lets look at a few differences with the Clog manufacturers marks. I am thinking that the "Clog Made In Wales" mark is the earliest. Then "Clog Wales", then the "Clog" word within a oval outline. When looking at Clog nuts there are three variations. First generation is "CLOG and number," only letters and number. Second generation is the "CLOG" word within a oval outline and the nut number outside the oval. Third generation is "CLOG" word and nut number both within oval outline.
Clogwyn 1974 catalog from Denis Pivot sent to Stephane Pennequin. This 1974 catalog mentions that a new King Pin design was created incorporating a extended anvil on the hammer end to prevent the deformation of the piton eye.
What is interesting with these two pitons is that the "Clog" and "Wales" words on the piton are designed for the pitons to be read diagonally.