THE TOP 20 UNDER 20

15. NATASHA WATSON Who? The primary pupil acting with Hollywood stars.

Why so influential? She's the youngest-ever Bafta nominee.

After her debut film, Iota, the director Simon Dennis tipped Natasha for Hollywood. "When Natasha came in for her audition, everyone just stopped what they were doing.

There was a special X factor that you almost never find. It was blindingly obvious that she has a big future as an actress." For her portrayal of twins in Iota, for which the sixyear-old learned sign language, she received a Bafta nomination. Now flexing her thespian muscles on River City, she's finished shooting the film A Woman In Winter with X Men star Brian Cox. She says her ambition is to "sing and dance and act in Hollywood".

16. JOSIE VALLELY Who? Scotland's top teen environmentalist Why influential? She's keeping our beaches clean and the government in check If the Queen ever reads her mail, she'll be familiar with the name Josie Vallely. And her letters aren't fan mail. "I've written to her on two occasions about how she sets a bad example, " says Josie. She has scolded Her Maj on her support for clipping pedigree dogs tails amongst other things. "So I told her I didn't like that." Her local MP and Tony Blair have also been on the receiving end of some stinging missives from the 16-year-old.

Thankfully Josie, from Edinburgh, does more than just write letters to the great and the good. She is a tireless volunteer at Gorgie City Farm, she organises beach clean-ups, has housed delegations of refugees from Africa and Palestine ("They had crazy rituals for making tea taking over the entire kitchen, " she recalls), and has set up her own website to advise other teenagers on how to save the world. So why does she do it? "It makes you feel better, " she says. "It's good to improve your immediate environment. It's also important that we protect the entire world, as it's us who will have to look after the mess that's being made at the moment." Her campaigning has taken her to eating fish cakes with Bob Geldof at the Make Poverty History march and personally congratulating Jack McConnell on the smoking ban, to being awarded CosmoGIRL campaigner of the year. Her website, which was created in a bout of procrastination when she was supposed to be doing homework, has received hundreds of comments from around the world asking her advice on how they can be more green. She admits that the the sheer volume of posts scared her slightly, but that hasn't put her off. Josie firmly believes young people can make a difference - the key is to speak to people in power. "They definitely listen. People just don't realise, but that is their job - to listen to us. So they have no other choice."

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17. JORDAN MAGUIRE Who? The new Ranulph Fiennes.

Why so influential? He's literally on top of the world.

Like the needle on a compass, 15-year-old Jordan has been drawn to the north pole for most of his life.

And by the time you read this, the Glasgow teenager should have trekked the final 111 miles, dragging an 80kg sledge, and made his way into the record books as the youngest boy ever to walk to the North Pole. "I guess I've always had a spirit of adventure, " he says, hours before he gets on the plane to fly to Norway. "The North Pole has been a fascination since I was six. I want to climb Everest and go to the South Pole as well." Jordan says because the North Pole is in international waters, no special permission is needed to go there, "Aside from my parents".