I think this is Solution in the park in Groningen. They were an utterly brilliant live band in their heydays, up there with the best. I saw the band a couple of times in the late 70s. They opened with "Carousel".Great intro(Waterman). Shivers down my spine. I remember it very well. It's so unfair that they never got the recognition they deserved.
Amazing sound quality for being outside live in the 70s.
At first I thought they were faking along, but all the hand playing is in sync with the audio parts...but then where are the mics and amps, etc?