The stylistic authority is whatever it is for the place in which the name
appears; newspapers, magazines, books, all operate under the authority of
some formal style guide (of which there are really only a few).
If the use is not in a context for which a style guide is mandated (such
as an email), the writer in doubt can refer to his or her preferred style
guide. A common one is The Chicago Manual of Style.
The Chicago 14th Edition has entries for "English Names with Particles"
and also for Non-English Names, under which is the subheading "Italian,
Portugese, German, and Dutch Names". Under that, we read:
Particles . . . are lower-cased and are usually dropped when the
surname is used alone in the original language. In English, writers
have shown little consistency in their treatment of such names. The
frequent older practice was to retain and capitalize the particle when
the surname was used alone. Consequently, for some names the form
with the particle is the only familiar one and must necessarily be
used. For other names the native practice should be followed.
Examples given there include:
Giovanni da Verrazano; Verrazano
Lucia della Robbia; in English contexts, della Robbia
The text at "English Names With Particles" reads in part:
For names of this type borne by people in English-speaking countries,
practice with regard to capitalizing the particle varies widely, and
competent authority should be consulted in doubtful cases. Generally,
the surname retains the particle when used alone.
Not, all in all, definitive, but helpful.
--
Cordially,
Eric Walker