Subtle indeed. He may just be excited to be there, but it seems Obama has assumed the body language sashay of saying, "Hey, Gordo, I'm POTUS and I'm going first, AND I'll bend protocol with your guard if I like it, too"...

If you're inviting someone into your house, you either very overtly say "You first, please", and guide them in, or you humbly lead.

I wouldn't mind seeing some re-calibration of American superciliousness. We're all in the same big boat.

FWIW-That PC may be assigned to that detail, in which case he has probably already been introduced to the PM. If you notice, the PM speaks briefly to him, and after he turns, the Bobby extends his hand as though he's offering his hand, but the PM doesn't see it. Also, Obama offered his hand to him as he approached, so it would have been insulting to not shake his hand.

Good points. I still think Obama is pretty cool. He makes me proud to be an American again overseas.

Reminds me of the time I was in LA and I saw my first LA cop. I went up to him and asked to shake his hand saying, "I've seen all your movies!"