This weekend I scooped up an Oxford World's Classics copy of P&P at a second-hand book sale. It has an interesting note on the meaning of "candour" in Jane and Elizabeth's conversation back in ch.4:

Jane: "I would wish not to be hasty in censuring any one; but I always speak what I think."

Elizabeth: "I know you do; and it is that which makes the wonder. With your good sense to be so honestly blind to the follies and nonsense of others! Affectation of candour is common enough; -- one meets it everywhere. But to be candid without ostentation or design -- to take the good of everybody's character and make it still better, and say nothing of the bad -- belongs to you alone."

I always read "candour" to mean what it does today - sincerity or frankness, since the first part of the conversation, at least, certainly makes sense with the modern meaning. However, the OWC has this to say:

"R.W.C. quotes Dr. Johnson's definition of "candid":

"free from malice: not desirous to find fault"

...there is a reference to Pope's "Laugh where we must, be candid where we can" and ..."the ingenious lady in "The School for Scandal" (1777) had not Candour but an Affectation of it"."

If this was the meaning of "candid" at the time, then Jane certainly was candid! Interesting how being candid has come to be an excuse for pointing out people's faults!