I did a double-take at a photo caption in yesterday's NY Times: "Zara Phillips, a granddaughter of Queen Elizabeth II’s, was part of the team that won a silver medal in eventing on Tuesday."
"A granddaughter of Queen Elizabeth II's"—why the unusual double genitive (was the term originally Jespersen's)? Despite all the attention given to Zara Phillips, that phrase appears only twice in Google, excluding duplicates, and "a granddaughter of Queen Elizabeth's" appears not at all—this against more than 600 hits returned for "a granddaughter of Queen Elizabeth II" and "a granddaughter of Queen Elizabeth." (Google actually estimates 230,000, but you know how much that means.) The double genitive seems to be very rare when speaking of family members, even those of whom one can have an indefinite number, unless the genitive itself is realized as a pronoun ("a granddaughter of yours," "no son of mine"). But of course the construction is fine when one is speaking of friends, colleagues or other alienable relationships. Search me. There's an extensive literature on this construction, from several schools, including contributions by Ray Jackendoff, John Taylor, Barbara Partee, Chris Barker, Gianluca Storto, and a number of others (see the bibliography in Chris's 2008 paper), and no doubt this point is covered somewhere — but where?