Hey, good to see you again Draywoman.
And welcome to the site Argro!
I just went out and bought my copy from Waterstones and got chatting to the assistant on the check out when she commented that they were selling out fast. The only other book to get anywhere near equalling the amount and speed of sales today is Tony Blair's memoires!
From the tone of the conversation, however, I think Sir Terry is just ahead to pip it for the top spot, despite the media's mass advertising of Tony's book.
Not too bad really, considering that there doesn't seem to have been much advertising from Sir Terry's publishers (or have I just missed it).