Late in the evening, I ran into him and his wife on the bus when getting home from work - and started talking to them. Apparently, nobody from the department had arranged to take them out for dinner, so we ended up going out for dinner together, where we had a fantastic discussion covering religion, tolerance, and lots of other topics. I am a staunch materialist and atheist, while both the Walls are serious committed Christians, but we had a really pleasant discussion on religion and the nature of evidence.
I ended up giving his wife a copy of Hume's Dialogue on Natural Religion, and they were kind enough to sign a copy of the Camel book for a friend who is a huge Perl fan.
A lot of people know Larry by reputation - but his wife Gloria is just as smart and kind. It was a bit of a strange evening, but it was a rare privilege to meet two such interesting people.