Let me tell you a personal story:
Jethro Tull "This Was" was released on October 25, 1968. I was a 15 year old high school freshman. Just beginning my life long odyssey with the electric bass.
I heard Mick's seminal take on Cat's Squirrel on the radio, but did not catch who it was. That track sent a shock wave through my network of musical buddies. It took several days to track down it was the first album by this new band, Jethro Tull.
That track was what initially sold the album. I immediately ran out an bought it. I always wondered if that pissed Ian Anderson off.
I was in the audience for Tull's first American tour after the release of "This Was". Man I was pissed off that Mick Abrahams was not in the band. Nothing personal against Martin Barr.
As a side note, Glenn Cornick's bass licks on "This Was" are some of the tastiest walking bass riffs I had ever heard. Nothing technically challenging or aggressive. Just perfect for that quartet at that time. Glenn's bass playing on "This Was" was probably my first major influence.
In terms of style, Mick is probably my favorite guitarist. Here he is performing Cat's Squirrel live:
Mick Abrahams Cat's Squirrel Live