According to BetG there were only 100 made in July 1974 and on their order form they were called jetons but I'm still not sure if they should be classed as jetons or chips. I suppose they could have been the type that replaced the original jetons from 1961 up until 1971 but there were later types made with different writing on too.

Totally unknown until the 2019 find and still in great condition.