Why is a definite article required here?

Question

In conversation with 2 native German speakers, I wanted to translate the following:

At least that’s what old lady Calvin told me just before we left.

I said:

Zumindest ist es das, was mir alte Frau Calvin gesagt hatte, gerade bevor wir weggingen.

and they corrected me with:

Zumindest ist es das, was mir die alte Frau Calvin gesagt hatte, gerade bevor wir weggingen.

Now in English one can either say, "old lady(woman) Calvin," or "old Ms. Calvin", and the meanings, or, at least, the inflections, are distinct. In German if "die alte Frau Calvin" is the only option, then it is not clear to me how to make the same distinction. (By the way, Ms. Calvin is not a lady in the aristocratic sense -- as is clear from the lower-case.)

Answer 1

As soon as you're adding adjective attributes to a name, you need an article.

Frau Calvin hat mir das gesagt.
Die alte Frau Calvin hat mir das gesagt.
Die heute besonders auffallend frisierte Frau Calvin hat mir das gesagt.
Der immer freundliche Herr Calvin hat mir das gesagt.

For other types of attributes, this can be optional if the name can be understood as an ersatz title:

Der Stofftiger Hobbes wird in der Fantasie des Kindes Calvin lebendig.
Hobbes wird in der Fantasie Calvins lebendig.
also: Stofftiger Hobbes wird in der Fantasie von Kind Calvin lebendig.

However, we need the article again if there already is a proper title:

Der Affe Herr Nilsson lebt im Haus des Mädchens Prinzessin Pipilotta Viktualia.

Of course the article will disappear again with the usual rules, e.g. if a possessive pronoun replaces it:

Die Nachbarin Frau Calvin kannte den Täter nicht.
Meine Nachbarin Frau Calvin kannte den Täter nicht.

For reference, see Erweiterung von Nominalphrasen mit Adjektiven.

Eigennamen können nur in Verbindung mit definitem Artikel und in der Anrede mit einem Adjektiv erweitert werden: Lieber Peter, Liebe Marie, Werter Hermann Meier.

Answer 2

The slight different inflection carried by "old lady Calvin" (as opposed to "the old lady Calvin") is linked to "old lady" being a kinda-compound noun in the former. German doesn't do kinda-compound nouns the way English does, it has a much clearer distinction between what is and what is not a compound noun. Thus, "alte Frau" or "alte Dame" just aren't compound nouns. It follows that we use the "definite-article adjective noun"-structure of a nounphrase.

German also doesn't have established compound nouns built from those or similar ingredients. The best translation for "old lady Calvin" I can think of would be "Gevatterin Calvin".