they made my first one aso a wee blue thing with a couple of switches hi low and 1/2 think it had a wire speed knob also.Clarke made mine! 1983ish.
MIG/GMAW Welding goes way, WAY further back:
Mig Welding History: GMAW, Timeline and Pictures - Weld Guru
The history of GMAW or MIG tracks developments in power supply and the understanding of how that relates to the speed of a continuously fed electrode wire.weldguru.com
I did see some old welding engineering magazines indicating some research from russia.When I was researching the Paton institute (Ukraine) I think they were early pioneers maybe.
They don't say which process was used though.
I think Oscar Kjellberg of esab had an earlier oneThe first welded ship was built by Cammel laird in 1917/ Called the Fullagar. Worked very well apparently. They don't say which process was used though.
It was very carefully monitored to see if it was a worthy successor to rivets. And they say it was very strong and easier to repair.
Fullagar - The world's first fully welded ship
Fullagar was built 1917-1920 882 at Cammell, Laird & Company in Birkenhead, UK as the world's first fully welded seagoing ship.www.alustir.com
I think Oscar Kjellberg of esab had an earlier one