Tony Benn has always had something of a special relationship with Scotland; whether in solidarity with the 1971 Upper Clyde Shipyard protests or generally striving to save diminishing communities. He's in Scotland for the preview of part of a documentary about his life: My Last Will and Testament. In the questions section there's a discussion about Scotland's referendum on independence, something Benn was prepared for.

"It was the first time I had done a debate in Scotland about the independence issue and you have to be very careful, as you can give offence. There was an SNP Member of the European Parliament there, and an academic woman, who was giving a balanced view. But for me it's an emotional question – my mother was a Paisley woman, my father was member for Leith, and I've got a Scottish son-in-law. If Scotland became independent it would feel like my parents were getting divorced, I would be really upset by it. I think you have to be candid, but I don't know. I can't see Scotland voting for independence, can you?"

We talk about family and history, the ties that bind, and the complicated terrain of identity, referencing Parnell’s assertion: “No man has a right to fix the boundary of the march of a nation; no man has a right to say to his country, thus far shalt thou go and no further.”

“It is such an emotional issue and I knew it could get very excitable, and I didn’t want to release all that tension, but the conclusion I came to was that if they do vote for independence not much will change. I don’t imagine it will give Scotland the independence that they think it will, and that is a different argument to put forward.”

Benn has always put forward different arguments, considering communication the key to understanding.

We talk of his support for a united Ireland through non-violent means and the progress of Sinn Féin as a political force, and its policy of abstentionism (refusing to take seats) from Westminster.

“I wish that the Irish MPs had taken their seats at the time – but they felt they couldn’t – so then you never really heard the true Irish case in the House of Commons and, however sympathetic you are, you cannot represent it with the same passion and feeling.

“The decision to talk to the IRA was the most sensible thing we ever did and it created a completely new atmosphere.”

Benn’s policy of talking to those on the fringes has brought both positive and negative reactions, but he remains fearless.

“The people I am interested in, no matter what party, are people who say what they mean and mean what they say.

"Mrs Thatcher meant what she said, but the trouble was she had a signpost pointing in the wrong direction. The strength she had was that when people listened to her they knew she meant what she was saying, and that gave her a great advantage, because you have to persuade people. However, she was very oppressive and she dampened down any initiatives she didn't like."

Benn has always encouraged initiatives and ideas, something he harnesses in his 2010 book Letters To My Grandchildren, which is really about his hope for young people; to become not just part of the political process, but any process that drives towards greater harmony in society.

“You have to treat young people with respect. I am strongly in favour of votes at 16 – if you are old enough to marry, work, pay taxes and so on, then you are old enough to vote.

“And the one aspect of the referendum in Scotland that interests me most is the idea that the vote be open to people at 16.

“Young people are put down a great deal, and perhaps there is the idea that if you speak out you’ll be very controversial and difficult. There’s a tendency to be cowed into silence, but I don’t think young people aren’t interested in politics at all, I think the opposite.”

What advice would he give them? “You have to ask yourself what you are interested in, see what organisations are putting forward that view, then join with them. If you are any good they might ask you to take a larger role, because politics is about issues, not about parties. Parties are just instruments – people can become committed to freedom, independence, or peace; these ideas are what motivate them and you have to encourage that.”

So where does he think British politics is headed and does he think that Labour leader Ed Miliband might be someone who could enact a positive sea-change?

“When Ed was 15 he came and worked in my office for a month, and I have kept my eye on him ever since. I knew his parents very well, his mother I still see, and his brother I know too, so I voted for him as leader. I am encouraged by him. He is very highly respected by people; they don’t just see him as a kind of a new Blair, with all the drama associated with leadership.

“He is very thoughtful and careful. He is a great intellectual and has great understanding. He is receptive, not a bully, and he listens to people. I think he will win the election and will have a period of change, but when you are locked in as a leader of a political party, your scope for movement is quite reduced.”

Benn’s late wife Caroline once quipped that if he left parliament he might devote more time to politics. She died in 2000, and the documentary maps out how much of a partnership they had, how their sense of love and respect passed to their four children and how it trickles into his civic life.

“ Oh yes, it does,” he laughs. “Caroline was very beautiful and my greatest influence. She was very skilful, a strong personality, and had a clear mind, and knew what had to be done.”

True to his wife's advice, he left parliament and has been busier than ever. I wondered if he recognised any of the almost cartoonish backbiting in James Graham's play This House and Armando Iannucci's series The Thick of It, and if he missed it at all.

“Well they probably overdo it, but there is a savage side to politics which I don’t care for and don’t miss. If you can’t have confidence in people, even those you disagree with, then you lose confidence in yourself.

“I have often been greatly influenced by people I have met outside of that world that have expressed their convictions strongly and are prepared to suffer for what they believe, and I wish I had the courage they had.

“Sometimes I do these lectures, where the public ask questions, and it is always really interesting as they are non-political, and those people are not necessarily there because they agree with me. I learn a lot from those questions and really enjoy those discussions. The system should reflect the people, not the people start to reflect the system.”

Benn’s diaries, published in several volumes, provide a fascinating insight into the workings of politics and personalities, and a compelling account of social change over a long period.

“A diary is someone you talk to at night without boring anyone. Initially I used to keep a little notebook and wrote things down that interested me, about the girlfriends that I had at the time. I had one or two that I greatly admired, though I can’t say there was much response,” he laughs.

“Then gradually it became a diary. You know it was illegal to keep a diary during the war because the principle was that if the enemy caught you it would help their intelligence, so all my key words were in Morse code. I gave up my diary two years ago, as I was taken into hospital as I had a stroke and I stopped doing it, perhaps one day I will start again.”

This is partly why Benn is beloved by so many; his tenacious spirit and sense of joy in public service. If he isn't performing The Writing on the Wall with folk musician Roy Bailey, or appearing at Glastonbury, he is convening meetings as president of the Stop the War Coalition, or contributing to Michael Moore's healthcare documentary Sicko. He is always keen to disseminate ideas, listen and encourage. He wants his gravestone to read: "Tony Benn – he encouraged us."

“That would be it. I always wanted to be in parliament, and got elected when I was 25. Then I was elected a minister, and so on, but I have never had a particular ambition except that.

"I have been very lucky. I have a wonderful family, great interests, lots of friends, some successes, and quite a number of failures. You have to learn to live with yourself, which is quite a difficult thing to do and truth doesn't really protect you from malicious attack, but it is a form of protection."

The Last Diaries: A Blaze of Autumn Sunshine by Tony Benn (edited by Ruth Winstone) will be published on October 24th by Random House.