Kathy is one of four directors-general at SIS, each of whom reports to the chief, known as "C". For the first time, three of them are women. They work in the most important and rapidly evolving areas of spycraft. Kathy is director of operations. Rebecca is the chief's deputy, who oversees strategy. The most storied MI6 job of all belongs to Ada, who is the head of technology, known as "Q" after James Bond's mastermind gadgeteer. I have spent six months interviewing them about how they reached the top in a traditionally male career and trying to understand what the life of a female spy is really like.