Claps mathanxiety.
On a human level, I feel desperately sorry for Samantha Cameron in many ways. She's the product of a very unhappy marriage, she's nursed a child through a dreadful illness, she lost that child in shocking and desperate circumstances and must still be full of grief for him. A difficult role in a contentious environment is the last thing she needs. She's a creative director of a stationery firm; quietly designing in an office is a world away from hanging out with Mobama at the White House in front of the world's press.
But for whatever reason, she's decided to wants to support her husband and be by his side in his corporate role. Men can rarely force their wives to do anything - Camilla Parker Bowles does the minimum number of public engagements she can get away. And the simple fact is, if you want to be taken seriously, you've got to look absolutely appropriate for your profession, your level of seniority, and your audience. If you work in fashion, it's fine for your clothes to be noticed before you are; if you're involved in international diplomacy, it isn't.
And male leaders don't escape style criticism - if you're as old as I am, you probably remember Michael Foot and the amount of ribbing he used to get. Pratibha Patil is the female President of India, and when her husband wore a pullover under a pinstripe suit during a state visit to the UK, he was ripped apart for it in the Indian press.
Tony Blair had a huge amount of media and presentation training, as did Gordon Brown. They both looked dreadful before the Labour Party invested in branding - and the public appearance of their staff was as important as their new logo.