Ken Follett

This is one of the things I first learned about researching this book.

The best flint is underground.

The kind of flint that you can find just lying around in the fields and so on.

I live in Hertfordshire.

There's quite a lot of flint in Hertfordshire.

In fact, the barn attached to my house is built of flint.

But that flint is not really good enough for tools.

And the best flint is found underground.

So there are flint mines.

And in England, you can visit them.

There's a place called Grimes Graves, which is a historical site.

And you can go down the flint mine.

And it's very like a coal mine.

Coal mines, of course, did actually go down a heck of a long way, about 30 feet down, about 30 feet down.

And then there's a layer of this very beautiful black flint that they chopped up.

And it's much better to sharpen.

If you take a flint from the field and try and sharpen it, it'll quite often break.

But the flint from underground is much easier to work.

So this is just like a coal mine.

There's a shaft.