Prog Rock in a roundabout way. I use the term for:
1. music you mostly can't dance to (or would want to),
2. using odd meters more than once in while,
3. a lead vocalist (with a not overly commercial voice) singing things other than "baby, baby, rock me till the juice runs down my legs",
4. hardly any or no single hits,
5. played with some instrumental skill,
6. they never do Johnny B. Goode as an encore,
7. long lyrics that either mean something or nothing, but the latter very elaborately
8. they do concept albums at least once in a while
9. they have more 10 minute than 2.30 minute songs
10. they never pitch the chorus at the end of their songs by a half- or full-note to make it sound more commercial.
11. real prog is British and its protagonists all went to English (or at least Scottish) public (= private) schools (US prog bands such as Kansas could never match the Brits for worldwide recognition, but remained largely a local phenomenon)
Tull ticks the boxes on all of those. Maybe they weren't bad prog, but they sure were prog (which to me is not an insult, I make jokes about it, but I also listen to it quite a bit).
In my German high school, once you reached 10th or 11th grade liking prog over "lesser forms of music" (such as Deep Purple, Black Sabbath, Status Quo, Kiss, Sweet, Slade, Uriah Heep) was mandatory (unless you were a musical outcast like me) and that meant liking
the five prog greats: Pink Floyd, Yes, Genesis, Jethro Tull and Emerson, Lake & Palmer as well as those prog bands that did not quite make it as big or as consistently big such as Camel, Gentle Giant, Supertramp (though they were probably always equally an AOR pop band too), Mike Oldfield=Tubular Bells, Triumvirat, Manfred Mann's Earth Band etc. Wishbone Ash was one band you were actually allowed to like irrespective whether you otherwise favored Status Quo or Jethro Tull, but they were an exception. And if you were extremely cool, you would say all of the above are crap and only listen to Frank Zappa. Plus a little McLaughlin and Cobham to the side.
I'd say that together with Genesis (Peter Gabriel and first two Phil Collins lead voiced albums) and Pink Floyd ("Echoes", Dark Side and Wish you were here), Jethro Tull ruled the canon of prog bands popular in Germany in the seventies. Households without either Aqualung or Thick as a Brick as an LP were few and far between. Tull filled huge halls in the seventies in Germany. I can't remember a school or youth disco where Locomotive Breath (one of the few danceable tunes of JT) wasn't played, that piano intro would always create sheer bliss on the dance floor back then. And Ian Anderson was widely regarded as one of the most charismatic frontmen, his lyrics fervently studied by all those proud of their Englisch language capabilities. New albums coming out by JT up to Too old too rock'n'roll (which caused some bewilderment among the devoted for sounding overtly poppy and commercial) were regarded as the gospel, hell, people even said they liked Passion Play
(which tended to be the third-most popular JT album after the other two mentioned above).
