Williamson was a Vermont native whose family moved to the West Coast, where both he and his older brother Claude, a pianist, carved out very decent careers. Stu was best known for his years with Shelly Manne, which began right about this time. He did make two albums as a leader for Bethlehem, but they're hard to find, too.
He meshed beautifully with Zoot, who was a solidly mainstream player. There's nothing in this session that particularly screams out "West Coast" (New Yorker Kenny Drew, in the middle of a brief West Coast sojourn, is also there to keep it anchored). But although Williamson made his career in California, he was more regarded as a musician's musician than an advocate of a particular style. Here's what Marc Myers of the JazzWax blog has to say about him:
Though he wasn't a blaster or upper-register torcher, Williamson's notes were always in perfect pitch while his lines were consistently romantic.And Steven A. Cerra of Jazz Profiles:
This [is] a guy whom Shelly Manne was described as: “A wonderful trumpeter and valve trombonist and an excellent all-round musician. He reads well; he has good time; and a good sound.”
...Stu never “mails it in” [i.e.: gets lazy]. He’s always working; always playing with a ringing clear tone; always getting the dynamics, just right. Like the true professional that he was, Williamson paid attention to the smallest detail when playing a composition and does justice to all of them. His consistency of interpretation was remarkable as were his solos with their masterful phrasing and interesting ideas.
Sims himself is generally thought of, and with good reason, as coming out of the Lester Young tradition, but his first and deepest saxophone influence was Ben Webster. You can hear both traditions in his playing: the love of melody, the sure sense of swing.
Joining Drew in the rhythm section are Ralph Pena on bass and Jimmy Pratt drums. Pena played with pretty nearly everyone on the West Coast, was universally admired, and died young. I can't find much about Pratt as a musician, but he made his mark as an technical innovator, inventing a bass drum muffler for the Gretsch company that allowed the drummer to control its tone.
Stan Getz in 1949 and Lee Konitz and Billy Bauer in 1951
None of them are anywhere to be found on Spotify or YouTube, but they're worth rooting around for. A month later, Williamson (on valve trombone) and Sims reunited for a recording session with Clifford Brown, which is findable.
In addition to the New Jazz release, there appears to have been a Prestige 10-inch scheduled but never released.
Oh, yes, and how did Zoot get his nickname? On his first professional gig, he played in the saxophone section of Kenny Baker's band. Baker had hipster-sounding nonsense words in front of every player on the bandstand. Somehow, his was the only one that stuck.