Comma after a year question

Is a comma needed after the year 1940?

The sentence follows: The composer was alleged to have said this to his secretary in 1940, about a seasonal song.

Following the principle that one should avoid breaking up the flow of a sentence as much as possible--and this includes unnecessary commas--it would make sense not to place a comma after 1940. Certainly it is not necessary.

Perhaps even better would be a simple relocation of the prepositional phrase to the beginning of the sentence, such as this: In 1940 the composer was alleged to have said this to his secretary about a seasonal song.

What we have here is a series of three prepositional phrases and a question about how to best express them all in one sentence so that the meaning is clear and syntactically correct. The big question is, which phrase deserves the most emphasis, or better yet, what is the most logical order for the three prepositional phrases?

I would argue the correct order should be as follows:

The composer was alleged to have said this about a seasonal song to his secretary in 1940.

Phrasing the sentence this way obviates the perceived need for a comma; in addition, it qualifies the song as a seasonal song earlier in the sentence (which may or may not be important, depending on how many genres of songs the composer is alleged to have discussed with the secretary) and places a certain emphasis on 1940 by having it be the last bit of information the reader sees.