What is this 1920s(Makes joke about a flapper & a old maid) painted/drawn ad? A radio show promo?

Found this today - it looks circa 1920s - because of the look + the mention of flapper - and has the names Cromwell Knox and Sydney Tivoli.
Is it a ad for a show(radio?) - I ask because in bottom right where the artist's signature would be is a measurement & note (4 1/2" wide cut off)

What is this?
Thank you for any help!

 

Can't find anything to connect the names Cromwell Knox or Sydney Tivoli to real people.

 

I'm finding references to Sydney Tivoli as an Australian vaudeville theater.

 

This is from a 1903 paper, which is well before flappers, but maybe it was an annual (or revived) revue:

 

Cromwell Knox might be this guy (or his brother):

 

Yes, a theater. Hence spelling and quotation marks. So Vaudevillian Cromwell Knox. Golf clubs must have been props for his act.

Debora

 

Here he is in 1926 in San Antonio.

https://idnc.library.illinois.edu/?a=d&d=VVN19261119.2.73&e=-------en-20--1--img-txIN----------

Debora

 

Thank you all!
PS - so this is probably an ad for a newspaper right?

 

Here he is in 1928 at the Sydney Tivoli.

https://nla.gov.au/nla.obj-58569860...28&partId=nla.obj-585741041#page/n49/mode/1up

Debora

 

I'd think it was a newspaper cartoon. 'Spect (early) association with golf adds value. There's more about performer if you Google "Cromwell Knox" and "vaudeville." For instance, he was the brother-in-law of the novelist Sax Rohmer (Dr. Fu Manchu.) Oh, and apparently it's Cromwell-Knox, a hyphenate surname.

https://idnc.library.illinois.edu/?a=d&d=VVN19270910.2.80&e=-------en-20--1--img-txIN----------

Debora