When I was a boy in Carlisle in the 1950s, the city was decidedly unpretty; we were taken by the school to look at places like Houseteads Fort and I thought boring, boring, it's just a load of old stones. Later, at Durham, I spent a year studying Roman British History, under Eric Birley, then the greatest expert on the Wall. I thought boring, boring, it's just a load of old inscriptions, but at least it will be a soft way to get a degree.
And so I went on into life, moved away from Carlisle. In the 1970s, I woke up one day and thought I know, I'll spend a whole year walking the Wall. For a book of course, but mainly for my own interest. I'd realised it was a Living Wall - back then full of people, not just boring inscriptions, and today, with a perfect cross-section of modern life.
As I approached Carlisle on my walk, I felt excited at going back to my roots, heading for the primary school I had attended. At the time, I had never realised it was on the actual site of a Roman fort. It had taken me 20 years to realise where I had come from.
In the 1960s, when I was doing a book about the Beatles, the hardest part was getting them to talk about the Beatles. The past bored them, where they had come from was a haze, they were only interested in here and now. I knew that Hamburg was huge in their lives, but they couldn't even remember how many times they had been there. Paul thought three, George thought four, and John had no idea, but then he had been stoned most of the time.
When I was in Abbey Road, during the making of Sergeant Pepper, I often picked up scraps of songs from the floor at the end of the night. Take them all, they said, they'll just be burned by the cleaners, which was what happened to 99 per cent of these scraps. They themselves had no interest whatsoever in such stuff.
They were aide-memoires when writing the book, showing different versions of their lyrics. I'd done the same when writing about Hadrian's Wall, keeping all the scraps, such as fort tickets and leaflets. They are as worthless now as they were then, except to me, but my Beatles scraps grew to be more valuable than the house I live in. Which is why they are now on show in British Library and will stay there, after my death.
The remaining Beatles are today fascinated by the Beatles, where they came from, how they got there, and collect anything about themselves they can. One of the reasons Beatles memorabilia fetches such a high price at places like Sotheby's is that people know, or suspect, that a representative of the Beatles will probably be there, waiting to bid.
At this moment I am writing a biography of Dwight Yorke. Aged 27, something rather amazing has just happened to him. Winning three medals in 10 days will probably never happen to him again. Or anyone else. Getting him to sit still and think back to his childhood when he is in the middle of all this is bloody hard. As it was with the Beatles.
Any childhood snaps, Dwight? Nope. School reports? Nothing. When he arrived from Tobago aged 17, he brought nothing of himself. Well then, your first game for Villa, you must have kept the programme? He just smiled, then his friend Brian Lara rang and he was on the phone for hours.
Tomorrow, when I see him, I'm going to try awfully hard to squeeze every last word, every trivial thought out of him about Barcelona. It will be a struggle, but I like to feel in 20 years' time, if I do get it all out of him, he'll be grateful to me. By then he'll be more aware of his roots, wanting to look back to where he's come from, remembering what he did in 1999.
In the end, we all become interested in our personal history. Some of us also become interested in our tribal history, even when it stretches back 2,000 years. In the end, history is all we have.