For someone like me, making a documentary - I don't kid myself. There's no influence at all. What I do is entertainment. I would even say much the same about the column I write in 'The Sunday Times.'

Few people have heard of John Hawkshaw, the engineer responsible for Brighton's sewers, but he also built the Severn Tunnel and parts of the London Underground system. Such figures, largely forgotten now, conceived an infrastructure that was perfect in its fine detail and intended to last for a century or more - as it has.

I hope I succeed in demonstrating that you may equally find compelling and significant narratives - stories that alter or add to our understanding of history - in unprepossessing places: a Victorian sewer system; a Cold War bunker; derelict hospitals.

Here in Britain, we can get a little bit snobby about American history. Yes, their history is not quite as long as ours. But it isn't all that short, either.

One of the reasons that Thatcher promoted home ownership is that it promoted responsible citizens with a stake in society. But another reason was that those people would tend to be Conservative.

The stakes are high in politics.

Like so many other grammar schools that flourished in Britain before they were abolished through a mix of ideology and political folly, Harrow County was a fiercely competitive institution, where all boys were taught to strive for excellence. It was precisely because of this demanding regime that results were so good.

Non-fictionalised accounts of horrific accidents, bereavement, and the outrages of officialdom tend to move us deeply.

There's much about the British Raj which I think is disreputable. It was rapacious; it was a sort of kleptocracy, and it was also racist. Indians were not treated as equals.

British-built railways in India helped the British to make money and maintain order; but, as a by-product, they served to unite the country, making it ripe for independence.

As a presenter, you have to speak with artificial energy and enthusiasm.

My eyes are at different levels, and my right ear's a bit bigger than my left - which showed up particularly in school photographs - so my mother used to call me her 'little Picasso.'

The advantage of trains over planes is that there is much less hassle. You can get up from your seat and stroll about; you're more likely to meet people, and, particularly if you're making a long journey, you can actually see the terrain.

For all those who experienced it, the Spanish Civil War was devastating.

I love a good meal on a train, and if I'm travelling on a discount ticket, the challenge is to eat more than the price of the fare.

My grandfather, who was always keen to promote living artists, staged an unprecedented exhibition of Peploe's works at Kirkcaldy in 1928.

My Scottish grandfather, John W. Blyth, was a man addicted to paintings. A manufacturer of linen, he spent all his surplus money on pictures.

No restaurant, however brilliantly situated, can give you the constantly changing views that you can see from a railway. Revolving restaurants at the tops of tall buildings try to compete, but spinning around is no substitute for speeding along.

People are obviously very interested in travel, including travel in Britain.

My favourite British line is the West Highland line. It was built across moorland where no one had succeeded in building a road. So everything in that area is there because of the railway line.

I don't think I've got a thick skin, but I've not felt particularly humiliated by the things which people think I would have felt humiliated by, such as losing my seat in 1997 and not being elected leader in 2001. In the second case, I felt relieved.

Three letters send a chill down the spine of the enemy: SAS. Those letters spell out one clear message. Don't mess with Britain!

I look back on my schooldays with a warm glow of nostalgia.

I do rather rejoice when people come up to talk to me about railways.