Q: Why did Vita hyphenate “Sackville-West,” but Hillary doesn’t hyphenate “Rodham Clinton”?
A: Some double names are hyphenated and some aren’t. In the case of longstanding double names, family tradition determines whether a hyphen is used.
For example, the British composer Ralph Vaughan Williams has an unhyphenated double last name. “Vaughan” is not a middle name; his family name is “Vaughan Williams.”
The same is true of Andrew Lloyd Webber, whose father was the composer William Lloyd Webber. Their family name is “Lloyd Webber.”
The English author Vita Sackville-West also inherited her double last name (but a hyphenated one) from her family.
The British royal family name is officially hyphenated too. While “Windsor” is the formal royal name and the one used in public, the Queen has decided that her direct descendants will carry a hyphenated double last name: “Mountbatten-Windsor.”
The decision to use (or not use) a hyphen is often not inherited but a matter of personal choice. One or both members of a couple getting married may choose to use the two last names.
They can decide to hyphenate them, like Farrah Fawcett-Majors or Chris Evert-Lloyd (who have since dropped their ex-husbands’ names), or not use a hyphen, like Hillary Rodham Clinton.
Sometimes a couple who keep their separate names may decide to give their children a double (either hyphenated or non-hyphenated) name.
As you can see, the only rule for hyphenating these new double names is that there’s no rule.