I've just been reading the Discworld Monthly newsletter and apparently the petition to get Terry Pratchett put forward for a knighthood now has a response from the PM. I don't know which PM it is (Brown or Blair) but it's actually a response from the PM's office rather than the PM himself.
As for what the response says, it's classic political nothingness. It basically says "thank you for signing the petition, but it doesn't necessarily mean anything as there's only 60 knighthoods per year and we won't say whether we think he's a likely candidate or not".
There's also the potential cynical addition of "and we've already sold all of the knighthoods for the next few years", but who would ever be so cynical about the government?