The problem c_v is that in a country with a population with circa 70 million, our Tony will take the view that although there's a million peeps who think that far from getting a knighthood he should be standing trial in the Hague for war crimes, in his mind, there are 69 million who are very keen to address him as Sir Tony. If there's only a million or two signatures opposing his knighthood (me among them) - he'll regard that as a ringing endorsement!
The petition won't make a jot of difference, unfortunately. The only thing it might possibly do is to take Her Maj' by surprise and cause her to wonder if she's rather misjudged the views of her subjects concerning Blair - but that's about it I'm afraid.
Tim.