Nobody could call Jonathan Powell’s career path dull. He seems to have the knack, or more likely the talent, of finding himself in all the most interesting places at all the most interesting times. He started his working life at the Foreign Office, where he helped to assist in the Hong Kong handover negotiations with the Chinese, took part in the German Reunification talks in 1989-90 and shadowed Bill Clinton on the 1992 campaign trail. And this was just the beginning.

For, in 1995, Tony Blair appointed him his Chief of Staff and, after Blair’s 1997 landslide election victory, Powell became the Downing Street Chief of Staff and worked at the heart of the corridors of power for the duration of Blair’s premiership. The next decade saw him at the centre of Labour decision-making, from the 1997 Election to the Iraq War. However, perhaps unsurprisingly for a former diplomat, it was his role as one of the lead British negotiators on Northern Ireland of which he is most proud, calling it “by far the most important thing I did in my life”.

In 1998, the Good Friday Agreement was signed, finally bringing some peace to that war-torn part of the world. Getting there, however, was the cause of many sleepless nights for Powell. “It was a very frustrating process. I had to go across the Irish Sea once or twice a week, as well as being Chief of Staff at Number 10 and they made you negotiate through the night about things which didn’t need to be negotiated through the night. At some stages, I was tearing out my hair about it. But, in retrospect, I am really glad I did it.”

Given the recent flares of violence in Northern Ireland, I ask him how durable he thinks the current political settlement is, “We are not going to go back to the Troubles again, but if anyone thinks you’re living in a fairy story where everyone lives happily after, you are not. We solved lots of problems, we solved a large part of the violence problem, but we haven’t solved the politics and we haven’t solved the sectarianism. There is a process of peace-building that comes after peacemaking that can take a very long time to solve.

“Once people separate like that, bringing them back together again is very hard. It takes a very long period of time.” The conversation turns to the internal dynamics of the Blair government, and in particular, the role of the Civil Service. Powell and the Civil Service did not always see eye to eye and he thinks that there are lots of ways in which it can improve, telling me, “There is a problem with the British Civil Service. It is probably one of the best civil services in the world but it hasn’t had really major reforms, although it has had reforms, since the nineteenth century and it really does need a change. The trouble at the moment is that it is very much a dynastic order and although we say people come in and out, they don’t really. People still join when they leave university and leave when they retire.

“One of the reasons why it is so hard to reform the Civil Service is because it is underpaid. As a result people don’t want to go into it and civil servants don’t want to leave because their pensions are too good. But we need to try and change that and we need to change the incentive scheme.”

At this point, it seemed appropriate to put to Powell the question every political-nerdcum-American-TV-geek is dying to ask: “Do you think No 10 is more West Wing or Yes Prime Minister?” His answer is immediate, “It is certainly not West Wing. I remember the Chief of Staff in the West Wing, who has died since, came to see me in Number 10. I thought he wasn’t coming for publicity but because he was interested, and then the next day a picture appeared in the newspapers of me and him talking. I know American politics quite well because I started off following Clinton around. So it is not West Wing at all, it is much more Yes Prime Minister. In many ways, Yes Prime Minister is a documentary rather than a comedy. There are an awful lot of home truths in it.”

Powell left Downing Street when Blair did in 2007, and soon after joined Morgan Stanley as an investment banker. Suffice to say, it wasn’t his calling, and he soon left. His next big venture was to set up a charity called Inter Mediate, which carries out negotiation and mediation in “the most difficult, complex and dangerous conflicts” in the world. It draws upon his experiences in Northern Ireland and is rooted in the idea that it is only through dialogue that any resolution can be achieved, a concept which lies at the heart of his new book, Talking to TerroristsHow to End Armed Conflicts.

Powell’s idea is that it is always good to talk to terrorists. Such a proposition does not pass without controversy; take ISIS for example. Following a week in which they have beheaded 30 Ethiopian Christians in Libya, many people would baulk at the idea of giving them legitimacy by talking to them. However, Powell believes we have to take a longer term view, telling me, “I have looked at the negotiations going back since the end of the Cold War and there are certain patterns which have emerged. One such pattern is that every time we encounter a terrorist group we say we will never talk to them, yet we pretty much always end up talking to them. “So my argument with ISIS would be… would we sit down with Mr Baghdadi now and negotiate? No, that would be ridiculous. He wouldn’t want to negotiate. But, if we look back at what has happened in the past, nor is just bombing them going to work. Even if we had boots on the ground, that wouldn’t solve the problem of ISIS. You have to have some longer term strategy. If they have genuine political support, and I suspect they probably do – it would have been very hard for 1,000 fighters to take over the town of Mosul without support from the population there – the chances are we are going to end up talking to them. So the sensible thing to do now is to open up a channel, as we did with the IRA back in 1972, a channel which can be used at some stage to negotiate through.”

However, Powell also argues that we will not be able to negotiate until we get to two things: first, “a mutually hurting stalemate where both sides realise they cannot win and it hurts them to carry on fighting” and, second, “strong leadership on both sides, which allows conversation to happen”.

I put it to him that this still does not answer the question of legitimising them. He tells me, “It is certainly true that armed groups really want legitimacy, they are desperate to be heard, to get publicity. There is a real issue there. The argument I make in the book is that legitimisation is a very short term thing. So, if you take for example the FARC, they started the talks in 1999 to 2001 with the Columbian government, they got legitimisation. Having been completely outcast, they were able to appear on national television. But as they made it clear in the negotiations that they weren’t serious and then rejected a perfectly good offer, they lost that legitimisation when they went back to fighting. So, all you get is very temporary legitimisation, which can be a price worth paying.”

However, whilst that might hold true for specific terrorist groups, I suggest that it still does not answer the argument that by talking to terrorists, you legitimise terror as a tactic. Powell, however, does not buy this, saying, “In normal life, you do not regard talking to someone as a reward and not talking to them as a punishment and thinking about that in terms of terrorism is useful. In talking to terrorists, you are not agreeing with them and that is the point. Talking to terrorists is not the same as giving into them. When we were talking to the IRA, we were not going to give a united Ireland down the barrel of the gun, regardless of the views of the majority of the people in Northern Ireland.”

Our conversation turns to the practicalities of talking to terrorists, which are not all that they seem. “It’s a difficult thing to do as terrorists don’t have a front office where you can pop in and have a cup of coffee and talk to them. So you find a way of establishing channels and it is funny that they work in very odd ways. For example, a colleague of mine who is trying to get in touch with Nepalese Maoists went into Kathmandu and tried everything he could to meet them but didn’t achieve anything. But then he fired off an email to which is a website they used in homage to the Maoists in Peru, and to his great surprise he got a reply, and over the next few months, they worked out how they could meet. He went to a small Indian city, was picked up in a motor rickshaw, taken through some tiny streets, into a building, out of another building, into another rickshaw, and ended up in an unfinished skyscraper on the fourth floor and then a member of the politburo came and met him. So it can happen in very odd ways.”

This vignette, whilst not of Powell himself, certainly conjures up the excitement that suffuses the world of international diplomacy. Ultimately, however, it’s neither the excitement nor the glamour of Powell’s job that make his life’s work so enviable. Rather, it is the fact that what he is doing actually means something, namely opening up dialogue where there was none, whether in Ireland or Africa, China or South America. It is this raison d’être which shines through in this interview, and which makes his life of diplomacy so interesting.