I think this is the first time I have seen an Optimus 350 in one of the military boxes. From what I have seen previously there was a run of Optimus 300P lamps in various variations and then a big gap to a bunch of later model 1350 and 1550 lamps. The instruction card (showing a 300P) was usually tacked to one side of the box. Are there any marks on the lamp? Sometimes there was "ITT" stamped into the base rim of the tank. The one shown is one of the first variations of the 350 (the photos a bit shaky so it's hard to be certain) so would be from the end of the 1950s. The other sets I have seen would be from the start of the 1950s and then again from the late 1970s and 1980s.
As shown in the sign, the lamp has come to the Danish army in April 1954. I have taken a new photo of the sign which is now clearer. At the bottom edge of the fuel tank is a king crown and the letters ITT meaning (Engineering Troops Technical Service). Hope you get some more out of it, or write again. Tom
The instruction card (or sign) was printed in April 1954. The lamp itself is after 1957. The Optimus 350 model was first introduced in 1957 and this is the first variation so it is from 1957 or soon after. I must admit that this is the first time I have noticed the date on the sign. I wonder if there were different versions of the sign as well. I have a couple of Optimus lamps that are earlier than 1954 that have "ITT" stamper on them. Both with and without a crown.
I had an Optimus 350 which had a knackered tank and the link below shows what I did with the rest of it, I could not use the original Optimus base plate because of the indented meths trough, so I had to use an Anchor one. https://classicpressurelamps.com/threads/vikingson-cobbled-lantern.1878/
