Had a walking tour with Chris Cochran.
My wife and I were the only members of the group and it promptly started raining so I didn't have high hopes. However, in fact, Chris was knowledgeable and gave us a really good tour of the centre of Oxford. Historical buildings, college quads, filming locations - he covered them all. He even carried on the tour for longer than he was obliged. All in all, a very good experience and recommended.