T.V. Buttrey, a well known academic in numismatic circles, posted this critique of Lord Renfrew's views and those of others in the archaeological community who hold that unprovenanced objects should be treated as illicit: http://groups.yahoo.com/group/Unidroit-L/message/3220
The post is particularly interesting because it highlights not only the intellectual problems with Renfrew's views, but also the fact that academics who disagree with Renfrew and his adherants are subject to being "blackballed." I have heard this before privately, but have never seen an academic state as much publicly.
Another note on Lord Renfrew. I have also heard from several sources that he has a collection of Etruscan coins! I have not heard that the collection has been published. It would be interesting to learn more details, particularly about the coins' "provenance."