Stella Rimington talks about her career in Britain's MI5, of which she was appointed director general in 1992, and the heroine of her thriller series, MI5 agent Liz Carlyle.

How is the MI5 that Liz Carlyle joins different from the agency you joined in the late 1960s, particularly for women?

When I joined, women were really restricted in what they were allowed to do. It was really a two-tier career system. It was a different era altogether. Women were restricted to dealing with the clerical end, the papers, sorting out the files, doing a bit of intelligence assessment or analysis if we were thought to be quite bright. But the "sharp end" intelligence work—dealing with the sources and doing the sharp end of the investigation—was completely off the map for women in those days. As the '70s came along, with women's liberation and sexual discrimination reform, etc., we women who had degrees and were well educated were actually very similar to the young men that they had started to recruit. Gradually things began to change and we were allowed, rather tentatively at first, to move into more of the sharp end work.

How is Liz's career path similar to yours?

It's broadly similar. Again, you have to cast your mind back to another era. When I joined, it was the height of the cold war. The majority of the service's work was counterespionage, countering the efforts of the Soviet Union and its allies to spy and subvert Western democracies by spreading world communism. But then countering terrorism began to be very important in the U.K. because we had our own homegrown terrorism in Northern Ireland. So I spent most of my career in a mixture of counterespionage and counterterrorism. So Liz Carlyle's career slightly mirrors mine, but in a more modern, up-to-date way.

The plots of your novels are always very topical. Do you plan books around current events?

Yes, I do. I'm obviously very interested in what's going on and I keep a sharp eye on it. I do see in various current events the elements of a plot because I'm interested in what lies behind what one's actually reading. For example, with my latest book, Rip Tide, I read that some young British people had turned up in Somalia and that led me to wonder how they got there. And that became the plot of Rip Tide: how do young men who are brought up in the U.K. end up fighting with al-Qaeda in Somalia?

How closely do Liz's experiences resemble that of an actual intelligence officer?

One of the things I had to avoid when I first started was having Liz in meetings all day because in her "real" life she'd spend quite a lot of time discussing the situation and working out what to do next back at the office rather than out on the street. And that does not make compelling reading! So I've had to inject more frontline action into her life that might not perhaps be entirely and totally accurate.

As the former director general of MI5, are you required to submit your manuscripts for security clearance?

The rule is that if you've worked in the "secret world," anything you write that can be seen to have any bearing on your employment, you've got to submit for clearance. I submit the novels at manuscript stage for clearance; they read them; and occasionally they ask me to change the odd thing. Although with me it's been more than 10 years since I've had access to any secrets and I'm out of date with all the technology, their line, which I understand, is because I was the director general, people who read my books may think that they are entirely authoritative. So if I say something, even in my innocence, which actually turns out to be rather close to what they're currently doing, then they'll ask me to change it.