Quotative inversion is discussed in the style guide The Right Word at the Right Time: A Guide to the English Language and How to Use It (p301). It has this example:
'No, you cannot,' said Mrs Robinson.
It goes on to note:
Certain modern writers...dislike this convention, and insist on
retaining the usual word order. ... This blanket objection seems
In three specific cases, however, inversion should be avoided. First,
when the subject is a pronoun rather than a noun.
- ?'No, you cannot,' said she.
This now sounds laughably old-fashioned.
The second case is all too modern, in the view of many purists; that
is, when the presentational material comes at the start of the
- ?Said Mrs Robinson: 'No, you cannot.'
Associated with American news-magazines in particular, this rather
awkward structure is now fairly common in the journalism of Britain
and other English-speaking countries as well. Avoid using it unless
you are quite sure that it is in keeping with the style of the
publication or acceptable to your readers.
The third case in which inversion should be avoided according to the style guide is with 'more complex' verbs such as admonished.
The OP's sentence is a second-case example, and according to the style guide it is most often found in newspapers or magazines. The special language of newspapers is commonly called journalese. Further evidence for regarding this usage as journalese comes from Social Stylistics: Syntactic Variation in British Newspapers. The author cites a work by Crystal and Davey (Investigating English Style. 1969) which notes in the section on journalese that:
Verbs of speaking, such as say, declare or explain are often
inverted with the subject as in Said Dr Mason... .
So, the usage is not ungrammatical but fairly rare and may momentarily distract the reader.
Inversion - Wikipedia
Quotative inversion: Language Log
Social Stylistics: Syntactic variation in British Newspapers (Google Books)