The girl set to live with Wills

She is 19, a former public schoolgirl who loves all sorts of sport and spent her gap year in Chile. He is also 19, a former public schoolboy who enjoys skiing, water polo and rugby, and spent his gap year in Chile.

It should come as no surprise, then, that Kate Middleton and Prince William, both of whom are also studying History of Art, are planning to live together in St Andrews when they move into a rented flat for their second year at the Scottish university.

For the first time, today, friends have spoken of the "caring, outgoing" girl who will share her day-to-day life - and her bathroom - with the future king of England. One said: "She is one of the loveliest people I have ever met - really kind and caring. And while she is gregarious and has lots of friends, she could never be described as wild."

Miss Middleton is a first-born child and prides herself on setting a good example for her younger sister and brother. Her country upbringing is another thing she has in common with the prince, who spent much of his youth at his father's Highgrove estate in Gloucestershire.

She grew up in rural Berkshire and was educated privately, first at St Andrews in Pangbourne and later at the £5,470-a-year Marlborough College in Wiltshire.

Friends at the school, where her sister Pippa, 18, and brother James, 15, are also pupils, describe Miss Middleton as sporty but shy. One said: "Kate was captain of the tennis team, a member of the hockey and netball teams, and a keen cross-country runner - there was hardly a sport she didn't play. She was very pretty but also quite shy, and a bit of a mummy's girl, so the boys didn't notice her as much as you would have expected."

A boarder of the all-female Elmhurst house, Miss Middleton made many friends in her year, and found it equally easy to do so at St Andrews. As well as the prince, she will be sharing her digs with Fergus Boyd, 19, and a fourth student .

One friend said: "Kate is in the same hall as William, St Salvators, and they both do the same course. But she isn't going out with him or anything like that. They are good friends but I think she's closer to Fergus."

Mr Boyd was educated at Eton, like the prince, and spends his holidays at his parents' house in Wiltshire, while Miss Middleton returns to her parents' detached house in the pretty commuter village of Bucklebury, near Newbury.

Her parents Carole, 47, and Michael, 52, run a mail-order children's party toys business called Party Pieces, and in their spare time are keen dog-walkers on the Berkshire Downs. They have lived in the village for five years, and are popular with the neighbours.

One said: "They are a really lovely family and great fun - very partyorientated. We haven't see a lot of Kate recently as she has been away at university, but she is one of the loveliest people I have ever met. She is very outdoorsy, always doing some sort of sport, and she loves to get away to the coast to go sailing when she can."

Miss Middleton, currently on holiday with her family, recently stunned fellow students by modelling a see-through lace dress and black bra and pants in a charity fashion show at the university, with William cheering her on from his front-row £200 VIP seat.

She is also credited with persuading him to stay at St Andrews after reports that he found it "boring".

A friend said: "University may be boring after the rigours of Chile but life here is difficult in other ways, particularly for William with all the attention he is getting. He could not have chosen a nicer, more down-to-earth friend to help him through it."