Behind every successful man there is a woman – and behind every unsuccessful man, there are two," Mark Twain once wrote. He may have been joking but it has never been truer that strong monogamous alliances breed stratospheric success, especially in Westminster. Upcoming contenders for high-flying careers in this world must note: the secret to a power coupling consists of selecting very carefully – and hanging on to for dear life – a power spouse. In moments of doubt, the young and ambitious should ask themselves: Who in all honesty would have heard of Hillary if her surname had not been Clinton? “The Westminster bubble is small and quite hermetic,” explains Marie Le Conte, author of Haven’t You Heard: Gossip, Politics and Power. “Whether you’re a journalist, adviser or politician, you will be working very long hours in a space the size of a small village. The line between professional and personal becomes a blurry one after drinks in Strangers’.” Or, as one of her Labour sources puts i...