Models?present creations by British designer Stella McCartney as part of her Fall/Winter 2012-2013 women's ready-to-wear fashion show during Paris Fashion Week March 5, 2012.[Photo/Agencies]

Stella McCartney sent models down the runway in sporty but sophisticated school girl outfits on Monday, as cutesy collars and flouncy skirts found an anchor in classic English tailoring and rich country tweeds.

The British designer presented a winter ready-to-wear collection that was young, fun, feminine and light in the spectacular grand ballroom of the Hotel de Ville, Paris' city hall, with its soaring painted ceiling, imposing arches and ornate chandeliers.

McCartney described the collection as English countryside meets "urban energy, colour and shine."

"It was very much the country girl discovering the urban edge," McCartney told Reuters TV backstage, adding that she tried to "mix the two worlds together but in an unexpected way."

At the end of the show, McCartney's ex-Beatle father, Paul, raised his fist in triumph, while singer Alicia Keys, her first time at Paris Fashion Week -- "It's like magic!" -- gushed.

"It's so beautiful, the colours are so vibrant but still so sophisticated and chic and strong," Keys told Reuters TV. "I just love her whole style so I'm really glad to be here."

A PLAYFUL POP

Hem-lines were short, torsos were tight, and electric blues and white whites gave a pop to silhouettes that still felt sensible.

Panels of stretchy blue fabric and glossy blacks were sewn together with warm tweeds in a streamlined patchwork to create body contouring, flirty dresses with flouncy hems. The look was sensual, smart and sporty, complete with a peek-a-boo of skin behind the shoulder.

The collection felt fresh and playful, with a nod of irreverence.

Blue and white striped collars, as one might see on a varsity letter jacket, found their way onto boxy coats and a herringbone below-the-knee suit dress.

Pretty little white collars in white organza popped up from necklines, swirling white embroidery adorned crepe bodices and sleeves, and jacquard -- which can look overworked and old -- felt young in precisely tailored long royal blue blazers.

McCartney is one of the few high-profile designers to refuse to use fur and leather, on moral grounds. In relying instead on crisp fabrics, her clothing escapes much of the heaviness and outrageous excess one sees at winter collections.

Stella McCartney brand is a joint venture with French luxury and retail group PPR, whose brands include Gucci, Balenciaga and Alexander McQueen. PPR said last month that operating profit from its luxury operations rose 34 percent in its fourth quarter.