On NPR’s Morning Edition, there was a report about Michelle Obama charming everyone in Europe. Here, I paraphrase the reporter:

... Michelle Obama's only misstep on the tour was wrapping her arm around the queen during her visit to Buckingham Palace. An anonymous Palace spokesman said that "We don't issue instructions on not touching the queen".
I just couldn't stop laughing after hearing that. It reminded me of something else I had posted earlier. I guess the Buckingham Palace protocol must be similar to Kindergarten rules from Ashwini's class. No touching, no pushing, no spitting etc.

Link to the AP report about “the incident”.