Dragons were great big fiery beasts capable of eating horses. They flew around the sky, licking virgins whenever they found one chained to a rock wearing nothing but a flimsy negligee and a tiara, and hoarded gold. They needed gold. With all that fire in their bellies they were very hot, so they could hardly sleep on blankets. The blankets would singe at first, with that horrible smell of burnt wool, then they would blacken and start to reek. Finally they would catch fire and anything flammable that belonged to the dragon, including the odd spare virgin, would get all crispy and ruined. Gold was the only thing to sleep on that wasn't hard and scratchy, because, as you know, gold is so soft that it's possible to bite into it and leave teeth marks. More than soft enough for a great big beastie like a dragon to sleep on. Dragons ate sheep, as a rule, or anything else that was easy to herd into flocks where one great big mouthful would scoop up several at once. Dragons were fundamentally lazy beasts, and didn't see any point in swooping around picking up snacks one at a time when they could have several at once and settle down for a proper meal.

The thing is, being so heavy, the flight of dragons has long been a mystery. People have said that they either couldn't possibly have existed, or that they survived by magic. It was magic in the world that allowed the dragons to survive.

Well that's rubbish. There's no magic now: it's very unlikely that there was any more magic back then; at least not of the sort that could keep a great, big, sheep guzzling brute like a dragon in the sky. No, the thing is, you see, that gravity wasn't as strong back then. This was when the earth wasn't quite as heavy because it hadn't accumulated all that heavy iridium from comets and asteroids like the one that wiped out the dinosaurs. In the lighter gravity, there wasn't as much of a force keeping the dragons on the ground, so they didn't need to be as strong to fly. But gravity got stronger, you see, and the dragons stopped being able to fly. As more meteors hit the Earth and the planet got denser and gravity got stronger (gravity being an inverse square law directly proportional to mass, as any schoolboy can tell you), it became harder and harder for the dragons to survive. In fact, it got so bad that they started having trouble breathing, so great was the pressure of the atmosphere upon their massive bulks, squashing them into the ground. So they sought safety in the sea, where the water could keep them buoyant and support them, and take some of the pressure off. The dragons were happy in the sea, because swimming isn't that much different from flying really. Over the years they adapted and evolved, slowly but surely transforming into beasts that were equally at home in the water as the dragons had once been in the air. They continued to herd their food into great big lumps and swallow meals rather than picking off snacks, and I hear tell that some of them still lick virgins, although the tiaras and negligees are harder to come by these days.

I suppose you want to know what they became, those dragons.

Look out to sea. Look out into the oceans and search the horizon for a great spout of water erupting from the surface as a great beast surfaces to take a breath before going back to herding his lunch. They still can't breathe when on land, those beasts. It's too heavy for them, which is why people rush to get them back out to sea when the beach themselves.

Those beasts, of course, are whales. And that's why the Welsh have a dragon on their flag.