Gibson 1942 ES125
The Gibson ES125 started out as the 1938 Electric Spanish, ES100. The ES100 derived its name from the price of the guitar & case, $55.00, plus the EH100 amplifier $55.00 for a total of $110, or rounded down to just $100 to make the EH100.
Shortly after the new EH100 appeared in the October 1, 1940 Catalog Supplement to Catalog AA, the price was raised and it was named the ES125 for the complete guitar, case and ES100 amplifier set.
Gibson electrical instrument production ceased somewhere around 1943 due to the war. The U.S. entered WWII on December 8, 1941...just one day after the bombing of Pearl Harbor. Shortly after, the country became active in the war effort. The Gibson instrument factory was thrust into the war effort, as well (making airplane skids and submachine gun parts). Because metal was scarce as well as most other materials used in guitar production, Gibson electrics were put on hold until after the war.
Once the war was over Gibson started designing new electrics, including the newer ES125, ES150 & ES300....all outfitted with a newer plastic covered P-90 pickup.
To sum up, the ES125 turned out to be a very popular student model throughout the 1950's until production ceased in the 1960's. The interesting fact is that the ES100/125 has a very colorful background and this page attributes the beginning of the ES125.