[rewboss]

Originally Posted by riverkid

Lots of things do. That's the beauty of corpus study, Rewboss. It shows us that there actually are certain overrides to established principles. Prescriptivists called these exceptions because they couldn't explain things well enough.

That's a straw man: I'm not taking a prescriptivist stance.

But odd as it sounds, there are times in speech where there are clear overrides of the present perfect. Tony Blair's was just one of them.

Yes there are. And there's precious little difference between an "override" and an "exception", in that both are deviations from a rule. The main difference is that "override" just sounds more like a rule; but if you think about it, an exception is in itself a type of rule.

"She's gone, ... yesterday" works quite well, in certain circumstances.

The key phrase here is "in certain circumstances". The circumstance alluded to by your use of an ellipsis is when the sentence becomes longer. As long as the sentence consists of only one clause, the present perfect together with the past adjunct sounds unnatural. When other clauses are inserted between the verb phrase and the adjunct, the connection in the speaker's mind becomes much looser; the adjunct is disassociated from the verb phrase and the subtleties implied by the perfect aspect by simple passage of time -- the speaker has modified his or her train of thought mid-sentence. This is extremely common, as anyone who has ever recorded and tried to transcribe a natural conversation can confirm. (The effect is especially noticeable in German, where grammatical convention often results in verb phrases being split, one verb remaining next to the subject and all the rest deferred to the end of the clause or eve the entire sentence; speakers who religiously stick to such conventions sometimes find themselves floundering at this point. Not surprisingly, these rules are beginning to break down.)

Whether you prefer to construct a new grammar rule along the lines of, "A past time adjunct with the present perfect is permissible when the sentence exceeds a certain length," or take the true descriptivist approach and say that in natural speech, speakers will frequently add a past time adjunct to a present perfect without bothering to go back and correct the verb phrase, is unimportant: both positions describe what is happening here, but one is expressed as a rule and the other is expressed as an observation.