I picked this cool trench cap up on ebay several years ago.  I have a collection of ~100+ British and Commonwealth badges.  I wanted to have a cool item that related to the Engineers.  

During the COVID quarantine, I joined a FaceBook group that would help identify and validate cap badges.  After inquiring about several in my collection ---and finding that many were "re-strikes" or fakes--- out of boredom, I asked about the cap badge on this cap.  

 At that time I didn't know much about the "economy badges".  I knew this badge looked odd for some reason.  They soon pointed out that this is a WW1 economy badge with the King George V marking.  

The conclusion is that this soldier lost his WW2 issue badge somewhere in the desert of North Africa.  Someone pulled this WW1 economy badge out of his kit and used it.  Just a theory.

  

Royal Engineers Trench cap and British dust goggles.  

(Dust goggles are what you see General Rommel wearing.  They captured a supply at Tobruk.)

   

The liner appears have melted to the top.  Maybe this was caused by exposure to the desert sun.

 

The melted liner has stuck to the top of the hat.

There is some discoloration which is not very clear in this photo.  

 

 Royal Engineers Cap Badges:  King George V (economy) and King George VI

 

 

 

 

General Services Buttons

The deterioration of the liner is quite common with older caps, I am not sure what causes it; it may just be age or a reaction to hair products such as brylcreem that were used at the time. Heat may well speed up this process. Regards the cap badge it may be that the owner joined prior to 1936 or could even have been a Great War veteran, and was still serving in World War 2. For example, the RAF they were still issuing great coats with King's Crown buttons after 1952.

44 minutes ago, numbersix said:

For example, the RAF they were still issuing great coats with King's Crown buttons after 1952.

Oh.  Good info.  I knew that the entire army couldn't change all their badges in buttons in just a few weeks or even a few months of a new coronation.  I wondered how that worked.