Over many years trading I have bought and sold this type of stand many times, sometimes round and other time square or rectangular. Most of the time stamped with a makers mark and occassionally, like here, unmarked -- have you guessed yet ???
Here are two more examples of similar ---
The lower version is the same pattern as mine but the construction of the legs differs, only 2 rivets rather than 3. This design is inherently weak and most examples that survive are usually repaired where the rivets have pulled through the copper. Both these examples a signed with the stamped KSIA mark !!
.... proof that they are all made at the Keswick School of Industrial Art in Cumbria, England. Also a similar shaped trivet can be seen on page 39 of the book The Loving Eye and Skilful Hand: The Keswick School of Industrial Arts - Click on title to find a copy.
Not really a mystery to those who know - yet it is reassuring that I can prove the attribution.