Flairck was a folk music project founded by guitarist Erik Visser and flutist Peter Weekers. They were always touring theaters. I’ve never understood why this was, but in those days there was a distinction between bands that were performing in the club circuit (places like Paradiso in Amsterdam) and bands that were touring theaters. And the two never mixed.
Flairck was popular when I was at high school in the 80s. I have seen them at the time, it might have been in 1988 (according to their website). I was impressed, but not enough to keep visiting them. This might also be because I stopped visiting the theater when I moved to Amsterdam.