CHAPDISC3: Harry stating the Order's HQ?

[Dave Hardenbrook]

No: HPFGUIDX 142826

I have a HBP Chapter 3 Question: Is the following a Flint? --

  "Our problem," he continued to Harry ... , "is that Sirius also
   left you number twelve, Grimmauld Place."

  "He's been left a house?" said Uncle Vernon greedily...

  "You can keep using it as headquarters," said Harry. "I don't care.
   You can have it, I don't really want it." Harry never wanted to set
   foot in number twelve, Grimmauld Place again if he could help it...

   
Harry is not Secret-Keeper for the Order, so how can he state in
front of the Dursleys that 12 Grimmauld Place is headquarters for
the OotP?  I must admit that I'm still foggy on how the Fidelius Charm
works anyway...

-- 
Dave