This issue of the Melody Maker magazine contains an article about the ocarina, which clearly wasn't considered a serious instrument by the fellow.
https://www.worldradiohistory.com/UK/Melody-Maker/30s/Melody-Maker-1930-06-S-OCR.pdf
Page 520 has an advertisement for Selmer brand ocarinas, and on page 542 there's the article.
The arranger can be heard playing his ocarina arrangement on this record (2:30):
He fails to execute all the tricks notated.