It‘s very odd, thought the girl.  Who could be walking, barefoot, in damp sand, on this freezing cold day?  She followed the footprints, resenting the intrusion of whoever-it-was.  This beach, which belonged to the tourists in the summer, was, she considered, hers in the winter.  Apart from a few people walking their dogs it was always deserted.
The boy was walking in the other direction and she saw him quite a long time before he lifted his head and saw her.  He was looking down, concentrating on a strange stick that he held in his hand.  It had a loop stuck to its lower end.  He looks as if he’s hoovering the sand, she thought.  He wasn’t the owner of the footprints; he was wearing boots with thick socks. 
“What’s that?” she asked him as soon as he came within talking distance. 
“It’s a metal detector,” he said, looking up.  “Who are you?”
“I’m Tuppence,” she said, “and this is my beach.  What is a metal detector?”
“That’s a peculiar name,” he said.
“Well, it’s Penny, Penelope really but my dad, my first dad, always calls me Tuppence, he says I’m twice as much, and it’s sort of stuck.  At school they call me Penny.  What’s yours, anyway?”  She hoped he had a name she could jeer at.
“It’s Brad,” he said simply, his attention entirely on the metal detector that was making a fast ticking sound.  Closer to, she saw it had a display that was flashing.
“What does that noise and flashing mean?” she asked him.
“There’s something metal under the sand.  It’s probably just an old tin can or something.”  He delved in the pocket of his coat and drew out a narrow trowel.
All resentment gone, Tuppence watched with anticipation.  What might he uncover?  The sea had washed up some treasures for her, she had a collection of beautiful shells, but this was a promising new way of finding things.  He was digging carefully and, when his trowel clinked against something hard, he took off his gloves and used his hands. 
“It’s a coin,” he said.  He rubbed it on his jeans to remove some encrusted dirt but she thought it was still rather disappointing, bent and discoloured.  Brad, however, was obviously delighted.
“How long have you been doing this metal detecting?”  She asked him.
“This is only my second time - I only started yesterday and I didn’t find anything but junk.  I’m staying with my uncle.  He’s an archaeologist and he’s got a really clever metal detector that tells you what sort of metal you’ve found and how deeply it’s buried.  He’s found some really important things – they’re in the museum.  This is his old one and he’s given it to me.  I can’t wait to show him this, he’s got some stuff for cleaning it properly.”  He put the coin in his pocket and drew on his gloves again.
Tuppence was rather disappointed that he had no treasure stories to tell, she wasn’t interested in boring old museum stuff. 
“How long will you be staying?” she asked him.
“Over the Christmas hols.  I go to boarding school because my parents work for a charity and move about quite a lot.  I usually stay with them in the holidays wherever they are but this year, well, they didn’t want to come back to England and they didn’t want me there because they’re very busy helping people.   I would have quite liked to stay at school, the others who do say they have a good time at Christmas but Uncle offered so, here I am.  I’m going to come back to the beach tomorrow and do some more searching, come down if you want a go.”
“Alright,” she said.  She was surprised to find herself liking him, the boys at school were stupid show-offs and never really talked like this, she thought. 
As she watched him hurrying away she remembered the footprints she had been following. She saw them now, overlaid by her own footprints, up to the point where she had stopped.  The tide had turned and waves were creeping up the beach, soon they would be washed away.  It had been a sombre, sunless day.  The light was fading fast and she was expected to be home in time for tea.
 She turned to make her own way home and saw a large, chocolate brown cat sitting on a sandy tussock.  It was watching her, intently, with brilliant amber eyes.  She stared back at it but, instead of sliding its eyes away under her glare, it went on staring coolly, unblinking, until she was the one to give up.  Really, she thought, what with someone walking without shoes, someone metal detecting and a peculiar cat, her beach was becoming quite crowded.