“You say that every single day!” said George. “It’s like a gramophone record! Still, I must say that I agree with you! Come on — let’s have a jolly good swim!”

They all plunged through the big, curling breakers, squealing as the water dashed over their bodies, cold and stinging. They chased one another, swam under water and grabbed at the legs swimming there, floated on their backs, and wished they hadn’t forgotten to bring the big red rubber ball with them. But nobody wanted to go and fetch it so they had to do without it.

Timmy and Sally raced about in the shallow waves at the edge of the sea. Timmy was a fine swimmer, but Sally didn’t much like the water, so they always played together at the edge. They really were most amusing to watch.

The dogs were glad when the children came panting out of the water, Anne the only one with a cap on her head. They lay down on the warm beach and Timmy flopped down beside George. She pushed him away.

“You smell of seaweed,” she said. “Pooh!”

After a while Dick sat up to pull on his blazer. He gazed over the bay to where Kirrin Island lay basking in the sun, and gave a sudden exclamation.

“I say! Look, all of you!”

Everyone sat up. “There’s someone on Kirrin Island, though we can’t see them,” said Dick. “Someone lying down, looking through binoculars at our beach. Can you see the sun glittering on the glasses?”

“Yes!” said Julian. “You’re right! Someone must be using binoculars to examine this beach. We can’t see them, as you say — but it’s easy enough to see the sunlight glinting on the glasses. Gosh, what cheek!”

“Cheek!” said George, her face crimson with rage. “It’s a lot more than cheek! How dare people go on my island and use it to spy on people on the beach? Let’s spy on them! Let’s get our own field-glasses and look through them. We’ll see who it is then!”

“I’ll get them,” said Dick and ran off to Kirrin Cottage. He felt worried. It seemed a strange thing to do — to spy on people sitting on the beach round the bay, using binoculars on Kirrin Island. What was the reason?

He came back with the binoculars, and handed them to Julian. “I think they’ve gone now, whoever it was,” said Julian. “I don’t mean gone off the island, but gone somewhere else on it. We can’t see the glint of the sun on their glasses any more.”

“Well, buck up and see if you can spy anyone through our glasses,” said George, impatiently.

Julian adjusted them, and gazed through them earnestly. The island seemed very near indeed when seen through the powerful glasses. Everyone watched him anxiously.

“See anyone?” asked Dick.

“Not a soul,” said Julian, disappointed. He handed the glasses to the impatient George, who put them to her eyes at once. “Blow!” she said. “There’s not a thing to be seen, not a thing. Whoever it was has gone into hiding somewhere. If it’s trippers having a picnic there I’ll be absolutely furious. If we see smoke rising we’ll know it is trippers!”