JKR's Edinburgh Festival Q&A is on her website now (under news)

[Lucy Zinkiewicz]

No: HPFGUIDX 110134

Well worth reading, for it clarifies a few things currently being 
discussed - for a start, JKR says Petunia "is a muggle", as opposed 
to being Muggle-born. And the spelling of the new character 
is "McClaggan". And it's not absolutely confirmed that the Hogs Head 
barman is Abelforth, though it seems likely. And I'm sure the wording 
of the two questions will keep people arguing for eons...

Lucy