Robert and I were talking about dreams and I asked him if he dreams in color or black and white. That led to a discussion of color in general. I commented that I always thought including "indigo" in the spectrum was dubious, done just to make the mnemonic "Roy G. Biv" work better. He had no idea what I was talking about! He made a bet with me that I wouldn't find more than a dozen google hits on that mnemonic - and there were over 13,000. The mind boggles.
Finally, he's working back in London now. This is good from my standpoint since it's a lot easier to get to than Stockholm and, more significantly, it's actually on the way to other places.