For a girl, there are many names to choose from- though I'm sure
Alexandra,
Elizabeth,
Mary,
Charlotte,
Anne and
Victoria are the frontrunners. There's also the possiblity that
Kate, a commoner by birth, would want to go with something classically English but perhaps uncommon in the royal English family. Middle names will certainly include at least one modern or modern-ish one.
I'd like-
Princess Mary Augusta Elizabeth Diana
The first three names are all common as first or middle names amongst English royalty, and
Elizabeth is
Kate's mother's middle name.
Augusta is a bit different, though, not as popular as
Alexandra and
Victoria amongst modern royalty, and
Diana is for obvious reasons.
For a boy-
Prince Arthur George Charles Michael
George is a common
King name, especially amongst the Windsors, and
Charles and
Michael are the grandfather names.
Arthur is also a
Windsor names, albeit a lesser known one.