The style set gathered at Somerset House yesterday for London Fashion Week's opening speeches and the first of more than 60 autumn/winter 2011 shows that will take place in the capital over the next six days.

"We feel bullish and excited about the week ahead," Harold Tillman, chairman of the British Fashion Council, said in his welcome address. "But this year is going to be tough – we have suffered alongside many other organisations from the Government's cuts."

If Samantha Cameron, who joined Mr Tillman on the podium, felt any discomfort at the remark, she did not show it. "I'm passionate about fashion," she said, dressed in a demure black Peter Pan-collared dress by the British label Mulberry.

"I'm here today because I believe we've got the talent and the expertise in this country to take UK fashion even further, and I'd like to do everything I can to support that."

The first day of the schedule was a showcase of the gamut that British fashion spans, from established names such as Maria Grachvogel and Caroline Charles, to up-and-coming young labels like Aminaka Wilmont and Jena Theo. The morning kicked off with industry stalwart Paul Costelloe's show.

His daughter, Jessica, was first to take a turn, and models wore pink crimped wigs. The Irish designer presented a vision of vividly coloured Harris tweed coats and skirt suits, cut in streamlined, boxy and trapeze shapes that recalled Mod apparel.

"The Boulevard Saint-Honoré in the late Sixties," Costelloe said. Warped mosaic prints in apple-green and blue, decorated skater-skirt dresses with pleated necklines, and traditional tartan and tweed was spun in surprising acidic citrus shades, suggesting that the summer trend for neon brights is set to continue.

Next came a sleek collection from Maria Grachvogel, the designer who once hosted Victoria Beckham as a model on her catwalk and has curated a successful range for Debenhams. This season the famous faces – including Seventies' supermodel Marie Helvin – remained in their seats and the clothes spoke for themselves. Inspired by the Grimm fairytales, models stalked through a salon of the newly refurbished Savoy hotel wearing pin-tucked and draped dresses printed with digitally manipulated feathers and forestscapes. There was plenty of black lace, rise-and-fall skirts in a palette of monochromes and stony neutrals, and the ubiquitous high-waisted, wide-leg trousers that were so prevalent at last week's New York shows.

The day continued with offerings from several past winners of the Fashion Fringe competition, a talent-scouting initiative that provides young designers with funding and mentoring to help set up their own business. Here was some of the youthful pep, vitality and edginess for which London Fashion Week is known. There was hexagonally seamed leather and jersey sportswear from the 2009 winners, design duo Jena Theo, cut in challenging asymmetric shapes that billowed voluminously with each step and were knotted and patched into Frankenstein-esque textures.

Floridian Corrie Nielsen, who was awarded the Fashion Fringe prize last year by John Galliano, made her first appearance on the schedule, with a collection that took references from the Elizabethans, the golden age of French couture and the New Romantics.

Bias-cut pencil skirts were draped and structured with origami folds, and the final look was a full-length black gown with puffed sleeves and gathering on the hips, which combined modern architectural style with something a little more classic.

Celebrations continued in the evening with a drinks reception hosted by Ms Cameron at No 10, with the likes of model Erin O'Connor, milliner Stephen Jones and Culture minister Ed Vaizey rubbing shoulders.

The Prime Minister's wife is creative director of the luxury goods company Smythson and has recently been appointed an ambassador to the British Fashion Council. She is known for supporting British fashion.

"People often say that fashion is one of our most important creative industries," she said. "Actually, I think they're wrong – it's one of our most important industries, full stop. It makes more than £20bn a year for our country, and it employs hundred of thousands of people."