Useful dinner table trivia, including
First, they don't always, and second, to protect their eyes from the sun's glare, which is the explanation the Secret Service gives on its website. The third reason is that a key part of the job is scanning the crowd for anomalies - the expressionless stare amid a sea of cheering spectators, or the overexcited member of an otherwise attentive audience - so it doesn't hurt that would-be attackers can't quite tell in which direction the agents are looking.
Shades might make them more identifiable, but it's a misconception that they're trying to go unnoticed: if they were, do you think there'd be such a preponderance of burly men with buzz-cuts in near-identical suits and ill-concealed earpieces?
If presidential protection were invisible, a stupid assassin might imagine there wasn't any, while a rational one might disregard it as an unknowable risk. In either case, they'd be more likely to shoot. Far better to foster the panicky half-awareness that the crowd is seething with agents ready to pounce.
Big summits are the world cup of politics. And as we learned from the 2006 World Cup, it doesn't matter how badly your other half fares on the pitch, you can still go home feeling like a winner if you dress the best. With Carla Bruni away, and Michelle Obama already feeling a little old hat (fashion moves fast), this could be the chance for an outsider to shine.
Step forward Sonsoles Espinosa, opera singer and wife of Spanish prime minister José Luis Rodríguez Zapatero. Previous public appearances have seen her working a range of looks from Pucci-esque prints to this sharp tux outﬁt, complete with skinny black trousers and heels.
History proves she knows how to wear colour too (witness one striking orange shift), and she has even been photographed next to Penelope Cruz and held her ground. Perhaps most importantly, she understands that even when circumstances present the most restrictive of dress codes, you can always let a good haircut and a piece of statement jewellery do your talking for you.