I never owned Low Spark, but some of my friends at the time of its release did, so I got to hear it fairly often--it's my favorite Traffic album (I did own "John Barleycorn Must Die"). Spark had some of the complexity of Caravan. I'm not sure what I'd think of it now, except that I still more or less remember the title track fondly.

I looked up the flute player--it's Chris Wood, who worked primarily with Traffic and some of their musicians on solo works.

Here's what prog with flute SHOULD sound like: https://youtu.be/Lhxf4oQm7Ck