I recently picked up a compilation of the Nationalteatern, leading lights of the Swedish progg music scene in the 1970s.
That's not a typo, the extra G is there for a reason. Progg was short for 'progressiv musik', an anti-commercial musical movement promoting alternative lifestyles and what might be broadly described as left-wing views. Some progg bands were also prog bands, but not all of them.
The progg scene was closely associated with similar movements in art and theatre, which is where Nationalteatern fit in. They started off as a travelling theatre company that incorporated music into their shows but gradually mutated into a band.
Nationalteatern haven't made any new records since the early 1980s but apparently still get together to tour every now and then. The live clip is from 1991.
"Speedy Gonzales" - Nationalteatern
"Ut I Kylan" - Nationalteatern