Having tried to find out what the British Constitution is, since reading Walter Bagehot late one night at St John's College, Cambridge, I've become a tiny moving particle in a big moving part of the British Constitution, which is the House of Lords.

It's even more baffling [from the inside]. But then, I don't want to find out, because it's a romantic thing, the British Constitution, a thing of shreds and patches. I think it suits us.

It would be agony if we tried to write it all down. It would take years, and we'd have immense fights. And also I like things to have an air of magic and mystery, which Bagehot did, too.

I'm one of those people who think we should go in for organic reforms rather than knock it all down and start again. I want to see a slimmer House of Lords, one where hereditary peers are converted into life peers so you don't have a by-election when one dies; to end the link between the peerage and the honours system, because it's a job, really - reforms of that kind.

I think bishops matter - apart from the fact that they're great fun and tremendous gossips. They do add something: there's no question about it. I'd firmly vote to keep a number of bishops in the House, even if we did have a largely elected chamber. No doubt at all.

Governments are so different, and the circumstances are so different within which each prime minister operates; so I'm not one to rate them. But the Coalition Government is fascinating to watch because of the emotional geography of it. Lib Dems, with one or two exceptions, are largely herbivorous politicians, whereas Conservatives are largely carnivorous, and these temperamental differences mean it's not easy for them.

It was the only thing that could have given us a period of stability in Parliament, given the parliamentary arithmetic that the electorate produced in May 2010. I don't think the alternative rainbow coalition was a runner.

I'm one of nature's optimists, but I do think that the Middle East is always in an immensely perilous condition, and the knock-on effects from, say, an Israeli attack on Iran's nuclear facilities would be immense. And that does make me fearful.

I think the greatest shared boon of our lifetime is the Cold War's ending the way it did. It's the most remarkable thing. That's not the only reason I'm optimistic - it's a temperamental thing.

Human curiosity - what Einstein called a "holy curiosity" - is within all of us, and it takes different forms. Mine was probably picked up from listening to family stories.

In the late '50s, my sister Kathleen, who was a history teacher, bought me R. J. Unstead's book Looking at History - that wonderful picture book. I can remember lovingly copying the outline drawing of a monastery. So, certainly by then, it was deep within me. And I found I enjoyed writing essays and stories; so the combination of my curiosity and the pleasure in writing fused, to make me a professional historian.

I've enjoyed it all in turn. I was lucky to do them in the sequence in which I did, because journalism is a young man or woman's trade - "routine punctuated by orgies", to use Aldous Huxley's description.

And I really loved every minute of the 20 years at the university that I was in from 1992. And the House of Lords is a place of fascination and delight - not just because of the great gossip that you get every day. As a historian of the post-war years, I can sit down every day and have lunch with some of my exhibits.

It's very pleasureable, and very illuminating, and an incredible form of adult education in the Lords, because people very often know such a lot. I knew it was a great repository of wisdom and experience, but I didn't realise quite how deep. Even deeper than I thought. And that's a great justification for it.

But the other reason for it is that it's very useful to have, somewhere in the legislative structure, a group of people - not just the cross-benchers, but really experienced people on the party benches - who are there primarily because they know things rather than because they believe things.

We're much more open than we used to be - amazingly more so than when I first started as a journalist, when there would be a leak inquiry if I mentioned the letters and numbers of a particular cabinet committee in a Times newspaper story. It's much, much more open. You just have to draw the line in a sensible place.

OTHER STORIES

Interview: Geoffrey Blainey, historian

‘Refugees not on the move are the most numerous and the most needy’

There are so many things that can go into the making of the psychic weather of a country and people at any one time. Governments are only part of that. They can surprise us all by rallying us at a time of great peril, when the rational prognosis is dreadful, and the classic example is of 1940. But there's a terrible tendency among politicians, most of the time, to use an old phrase of Yehudi Menuhin's: "drift to confrontation". The model is very adversarial in this country.

Politicians tend to love taking ideological and rather personal away days, and reducing things to primary colours and soundbites when it's all much more complicated, and that's why the public gets so irritated. So, if there's a general malaise or despair, they can add to it by not rising to the level of events, but sticking to the tribal reservations of both their minds and seating in the House of Commons, and only talking to their own kind. That's what depresses people.

But politicians are indispensable, and they can actually make things better. It doesn't have to be quite as raucous and coarse as it is.

It's the sound of freedom. If it was all muted, it wouldn't be a fully open society. I'm always a bit torn on that. Thank heavens we don't have a presidential system. That wouldn't sit well with us: we're much more of a collective in our approach to these things.

My wisest choice was marrying my dear wife, unquestionably - or asking her to marry me, much more accurately - in the spring of 1968. We have two daughters and two grandsons.

I regret that I lapsed from going to church from the age of 17 to the age of 54. I didn't stop believing. When my oldest daughter was going to marry a lovely Catholic lad from Liverpool, she said: "Can you take me to church, so I can start getting used to it?" And I thought, why on earth did I stop coming?

On a much lesser level - absolutely minuscule compared to that - I regret that I will not now write the book The Impact of Gossip and Rumour on the Making of Politics. But, for that, I'd have had to start taking notes when I was a young political correspondent in the mid-'70s. That's my scholarly regret.

I'd like to be remembered for laughter - grandad being an affable idiot. It would be nice if my books were read for a bit, but it's not right to expect people to do that, or crave it. They might like the jokes. And I have enjoyed the company of students, I really have. I hope I've never bored them.

I still have the most wonderful history master, Eric Pankhurst, who every three months sends me a packet of cuttings he thinks I ought to read, just in case I've missed them. He's a lovely man, and he had a great influence on me at the time, and never ceased to have an influence. There are people like Sir Michael Quinlan, Permanent Secretary at the Ministry of Defence, who was not only a great mentor of mine, but also a most wonderful human being; and John Ramsden, whom I worked with at Queen Mary College, a man of great character and verve - just two examples from each of my worlds.

There are probably about 20 people from my professional life who have gone on before and who I really miss: M. R. D. Foot, a historian of the Resistance, who was the most wonderful friend and companion, who died earlier this year. I've been really lucky - extremely blessed in that way.

The books that make me really purr with pleasure are the ones that slip down so easily because they're so wonderfully written. Professor Sir Michael Howard has a golden pen. And there's Dr Paul Addison, who wrote The Road to 1945. I remember thinking, I'd give anything to try and write history books like this.

Yes, I'm scribbling away. Always - scribble, scribble. The rhythm of the week wouldn't be complete without scribbling. I try - I fail - to write 1000 words a day most days. It doesn't have to be scholarship: it could be diaries or letters, to keep my hand in.

There was a sermon that Dr Rowan Williams gave at the anniversary of the Carthusian Martyrs at Charterhouse two years ago which really moved me. It was on the theme of martyrdom. It was the combination of his wonderful temperament, power with words, and the evocation he brought to it, in that beautiful chapel, surrounded by the brothers of Charterhouse and others. Magic isn't the word one should associate with religion, but it's the only one that fits.

Apart from being with the family, which is irrespective of place, I love being in the Lake District. My mum and dad were from the north, and part of the Fell and Rock Climbing Club; so they were always talking about the Lake District, and it really lived up to expectation when I went there. The Orkneys are a great family favourite, because of their austere beauty, and the fact that the winds are so fierce the midges get blown away - the little buggers don't stand a chance. My daughters thought for years that holidays were always cold and wet. They didn't associate them with sun.

OTHER STORIES

Interview: Emily Dugan, journalist

‘It was, sadly, the first time someone British other than the immigration authorities had shown any interest in them’

I always go back to the Sermon on the Mount. It's the thing we all sign up to without exception, and when we stray a few inches from that, we start falling out. It's the great thing we can all fall in on, as opposed to the terrible tendency we have in our Churches to fall out over everything. Best manifesto ever written: 175 words and no caveats. That's where I go if I need to.

I love Schubert. That amazing outpouring - there's hardly anything in there that doesn't bring solace. It's the great and most reliable transporter of mood for me. I can't play an instrument, sadly, though I did think that I might take up the ukulele when I retire so that I could do George Formby impressions and irritate everybody.

What annoys me? Apart from the silly little frictions of life like mobile phones on the upper deck of buses? When we score own goals in society, really. Like letting class or status infect every bit of education. I get quite cross about that. I'm not a republican in most things, but I do believe in the republic of the intellect. All this Russell Group stuff about "élite universities" - why can't we just get on with it? Good schools in every sector are beyond price, and I wouldn't do anything to harm Oxbridge, or public schools, because if you have places that give knowledge with aplomb and insight, that's important. But there's a disdainful attitude to some graduates because they come from a particular institution.

I profoundly believe in Newman's faith in university education for its own sake. I don't want to rant about this: I try to avoid ranting.

I'm happiest with the family, and when a piece of weapons-grade gossip that's very funny and not malicious comes my way. Also, I do love the reading and the writing. I'm very fortunate: work that's also play.

I'm not very good at prayer. I try. It matters. But I don't think that I'm that good at it. I find the form of words which come to me in normal social relations becomes a bit repetitive and stilted. I can be repetitive and stilted in normal life - of course I can. But this is difficult. I'm not one of those who can just chat with the Almighty. Words are never enough in prayer, are they? My consoling thought is that, if one got complacent in prayer, one would be in trouble.

Locked in a church with a companion? I think it might be St Benedict. I'd say to him: "That Rule is amazing, and it's very hard for civvies to apply it. I'm rather keen to have a better go at it than I ever have before. Let me tell you how I go about my daily and weekly routines." And I expect he'd sigh inwardly and think: "Not another one," but he wouldn't show it.

Lord Hennessy was talking to Terence Handley MacMath. Among his works are The Hidden Wiring: Unearthing the British constitution (1995), The Secret State: Whitehall and the Cold War (2002), Having It So Good: Britain in the Fifties (2006), and The Secret State: Preparing for the worst 1945-2010 (2010).