So many answers.
Drummer Pierre van der Linden was in the classic line up and still plays like a youngster dispite being in his 70's. Two superb drum solos and looking so comfortable and relaxed. He was possibly the star of the performance.
The guitarist has been with them for 25 years and looks like a cool dude. He was doing things just using hammer-ons and volume control, not pedals, that were spellbinding.
Bassist has also been there 20+ years and is the best jazz bassist I've seen. Playing a six-string bass, with seemingly too many fingers doing too many things!
Thijs Van Leer is old but still has it. He wasn't very mobile but he sure can hit the high notes! His jodeling was fast, random, bonkers. He still has perfect tune with his voice - my son and I both commented that his singing is still spot on.
The band came across as a very top-end jazz, prog-rock band. Very talented. I've never seen a 'rock' band as good.