Lambton Castle is on the banks of the River Wear near Durham. Long, long ago, John, Lord Lambton's spoilt young heir, was fishing for trout in the river. It was Sunday. "This is the Lord's day," said a passer-by. "You should be praying, not fishing!" The lad took no notice. He put a grub on the hook and cast his fishing line again. It hit the water with a plop.