Dear Ben Roth,
The Frank Chacksfield arrangement of *Twentieth Century Blues*, from his LP*
The Music of Noel Coward* (London LL1062 / Decca LK 4090, 1955) opens with
a brief reference to *Coward's Someday I'll Find You*, followed by a
measure of the glissando from the Gershwin *Rhapsody*, leading into the
refrain of *Twentieth Century Blues*. I don't think the Gershwin motive is
repeated later in the arrangement.
The only other instrumental of this song that I know of is on Norrie
Paramor's *The Magnificence of Noel Coward* (Polydor 2310-279, 1973) which
I have not heard.