Portillo cuts a suave, collected sort of figure. Little seems to faze this former Defence Secretary, even my bumbling slip-up when I proffer my first question; will Britain leave the world? He calmly pointed out that it was not possible for Britain to leave the world, but it was entirely possible that Britain might leave the European Union. Luckily, he’s on the phone and can’t see me pretending to shoot myself. His phlegmatic Britishness is perhaps not surprising when you consider the depth and breath of his career. In his time, Portillo has served in possibly the most important and radical governments since 1945, along with regular media performances and documentary making.

His advice to all those weighing up careers in journalism or politics? “I’ve often made a point to journalists who have not been in politics. I remember talking to journalists during the Blair years, when things were going badly wrong and Blair was under a lot of pressure. I would say ‘let me assure you that if you knew [what it was like], you would exchange your entire career for ten minutes of being in Blair’s position: it is just such an amazing feeling and such an amazing privilege to be in that position.’” Portillo during our conversation repeatedly described the work of a politician as being like “painting on…a big canvas”. Apt terminology perhaps, given his part in transforming Britain in the late 1980s and early 90s; Portillo was one of the most vocal voices expounding the benefits of the controversial Poll tax.

He claims not to miss the high-tension, cut-throat world of politics, however. “My present life is not in the least bit stressful, it’s just very, very enjoyable. There is such a diference between being a politician, where everyone snarls at you and distrusts you, and being a broadcaster where people constantly come up and say ‘Oh, I really enjoyed your programme.’” I imagine the famous Portillo-grin creeping into his expression at this moment. That same grin he wore at so many pivotal moments, even when he famously lost his safe seat to the eminently average Stephen Twigg (YouTube gold, great essay distraction).

I suspect this grin crept in a few times. I smugly contested that conservatism as a political ideology had lost its way. Since Thatcher, British conservatism has fundamentally failed to provide a positive alternative political vision, I suggested. A weighty topic, you might think. Not for Portillo. He let out one of those short, sharp, I've-heard-this-before-and-I-have-a-great-answer laughs and explained. "Thatcher defined conservatism largely by what it was against. So it was against vested interest, trade unions, high taxation and the Soviet Union. But the problem was she was very successful and got rid of all the things she was against. This left the Conservatives with nothing that they were in favour of.”

So what’s Portillo’s answer? Does the British Conservative Party have to return to its Burkean roots, or does the answer lie in Cameron’s tentative pro-localism philosophy?

The grin again: “I think localism is quite a good idea, but I don’t think it’s a defining ideology. Ultimately I can’t imagine people marching through the streets being excited by localism.” Instead, he explains, “this government, I think, is amazingly radical. It is reforming welfare, the NHS, schooling, at the same time as an austerity programme which means a pretty substantial revolution in the way we do government. Though I’m afraid they’re not very good at explaining this. Actually, in many ways, this is a more reforming and more radical government than Margaret Thatcher’s was and much more radical and reforming than Tony Blair’s was.” So, the conservatives have an ideology, according to Portillo; it’s just hidden. I protest that pragmatic pursuit of a set of time-sensitive policies is not equivalent to an ideology. His response: “in a way I am not sure it is as difficult as you and I are making it sound. What the government is doing right now seems to me a pretty good set of polices. What it is lacking is the articulation of what they are doing.”

Sensing that we were unlikely to satisfactorily tackle the higher realms of conservative political philosophy, I moved on to Cambridge, and its inluence on his career. Portillo is renowned for his good manners; so renowned that the BBC trusted him with 60 minutes of their much sought after time to sit down with a few guests at dinner and discuss pressing moral and political problems. BBC Four’s ‘Dinner with Portillo’ tackled the moral neutrality of science, Bush’s legacy and the plausibility of Scottish independence. Aside from all the fork clanking and having to watch Portillo’s outrageously well-defined jaw-line munching through an appetising looking steak, they are well worth watching. Many suggest Portillo honed these skills in the depths of the cosy dining rooms at Peterhouse. Here he moved in conservative circles which would later have a profound impact on Britain’s entire social structure.

These formative Cambridge years were clearly close to Portillo’s heart. “I look back at Peterhouse as being one of the great institutions of my life. I feel I owe such a lot to Peterhouse...I have a lot of respect for it”. His time here wasn’t always quite as simple as many believe though. The sherry-drinking, high conversation culture meant Portillo, “didn’t feel very clever at Cambridge. Looking back, in all sorts of ways, I failed to make the most of it. Yet even having failed to make the most of it, I look back on it as one of the most important formative influences on me.”

Portillo insisted that Peterhouse was not overtly political. He recounts a conversation with his influential conservative tutor, Maurice Cowling: “and he said to me: ‘it’s a pity you are not interested in politics, because if you were you might think of going into the Conservative research department.’ I said ‘well funnily enough, I am interested in going into politics and I would like to do that’, and he said ‘Oh I had no idea.’ So that is a real measure of it.”

The grin absolutely returned at this point. He spoke of Cambridge with a fond, warm tone; a happy time for him, I suspect. He’s coming back too: on the 10th February at the Arts Theatre. I would suggest you go. He will make you laugh and think. You’ll most probably gain a unique insight into the halls of power during a highly influential period of British history and – above all else – you’ll get to see that infectious grin.