That's brilliant Toritoribe. That all makes sense with the context. Forgive me for not originally giving you the background to the story. I didn't want to 'lead' your interpretation of the text.
The full story is as follows...
I bought the multi-meter from a lady who told me that her father had been a Leading Radio Mechanic for the Special Boat Section at the end of WW2. As an electrician, he was one of those given the task of removing the radar capability from Japanese Warships stationed in Surabaya, Java. The commanding officer gave him the boxed meter as a token of friendship, complete with the inscription and his initials 'RW' painted on the lid. The gentleman has recently passed away, aged 91.
I hope, like me, you have found this story interesting, and I thank you for your patience and immeasurable assistance in solving the mystery.
If I can ever be of assistance, please do not hesitate to let me know...I have added a photo of the meter just to complete the story.
Kindest regards
Jon