Kelly are the tidier offshoot of Selmer, this one in particular is very Selmery, had a good chance to side by side it.
Got them both from same dude, fairly sure he put the knobs on, but the chassis and such are clearly same.
That’s a timer so you can keep track of your valves.
Top side of chassis.
Underneath, familiar Kelly build style on tag strips. Some work done and a diagram left in there. Tagging Selmer, should bring up previous 100w Selmer PAs for comparison.