This is actually a rebadged Optimus lantern. It is from after Optimus bought all the liquid fuelled production from Primus and basically sold their own product labelled as Primus. This is most likely due to the Primus name being more popular in some markets. This model is seen in Primus catalogues from 1971 and 1976. there is an undated page that came with a 1967 stove catalogue, but there are some minor variations in style so could be later. So far we can say that the model existed from some time in the 1960s to at least 1976. I have seen several of these lanterns and can note three variations. The label can be either red or black. Red is the most common. A pressure gauge filler cap is also seen (this could be later production just like Optimus). The top is seen with either the name Primus stamped on the top, or like here with the Optimus logo. Funnily I have never seen an Optimus lantern with this top.