I'm a fan of Focus going back to the early seventies, and this track (along with  "Sylvia") was probably their trademark tune.  It was originally written "rock parody," fior the Moving Waves album, because, at the time, there weren't any actual rock tunes on it.

I heard the story of this version tonight, and I just had to track it down.  The original is, 6m 41s long, and heads towards ten minutes when they play it live as a rule, but they were told, late in the day, that their spot on this show was "now" less than five minutes, and so they went for it, big time.   Parody?  Comedy?  Whatever else it is, this is a great take on a classic Focus track.

It's also a bunch of top-class musicians not taking themselves very seriously at all, which I love.

I'm not sure what Thijs van Leer is on, but I'd love to know if only so I could keep clear of it.