I was in the signals division of our school CCF (less drill and more playing with radios!) and it was our job to lay communications lines on field day. I have vivid memories of laying (what seemed like) miles of field telephone wires over heathlands and through woods and soldering them together with these self soldering sleeves.
They had a part on them like a match head which you could strike to set them off. They would get very hot and melt the solder inside the copper tube allowing you to push the two bared ends of wire in which hopefully you'd manage before burning yourself or the solder solidified again! I think they were something like thermite - they certainly smelt like it.
The CCF had lots of WWII surplus stuff, like massive radios with valves in and really leaky canvas tents!