By Piya Sinha-Roy and Li-mei Hoang

LOS ANGELES (Reuters) - Designers at London Fashion Week heralded a return to ladylike elegance for spring/summer 2013 using florals, longer hemlines and tailored cuts to create a modest look with subtle sexuality.

A weakened global economy continues to weigh on the luxury fashion industry and London designers were keen to showcase statement pieces that buyers would want to invest in, drawing on the timeless silhouettes of the 1950s, as seen at Temperley London, Emilia Wickstead and Vivienne Westwood Red Label.

"London still feels creative and still has that exciting, buzzy energy about it, but the collections were full of highly wearable, luxurious pieces," Pat McNulty, web editor of UK's Cosmopolitan magazine, told Reuters in an email, citing collections from Giles, Burberry Prorsum, Erdem and Mulberry among her favorites.

The rich floral culture of the English countryside was a central theme this season, as designers incorporated vibrant blooms and floral colors into their palettes.

Floral motifs adorned garments at Erdem, Mulberry, Bora Aksu, Temperley London and Corrie Nielsen, who was inspired by botanical gardens and Japanese artist Makoto Murayama.

Designers favored lighter fabrics for their spring creations, using a medley of organza, cotton, silk and chiffon, but added a sexy edge with cropped tops and short hemlines at Felder Felder, peek-a-boo cutouts at Erdem and bonded leather at Mulberry.

WHIMSY AND FUTURISTIC FLAIRS

While designers may have embraced a more grown-up look for their garments, there was still a presence of the whimsical style that has made London fashion so unique.

Models at Osman rocked embroidered hearts that decorated dresses and separates with clean, sharp edges, in bold shades of pink, blue, yellow, black and white.

Vivenne Westwood, queen of quirky fashion, delivered a vamped-up 1950s housewife for her Red Label, with models walking the runway in painted faces and floral headpieces offsetting their feminine dresses and suits.

Elsewhere, bows were the rage at Meadham Kirchoff and garden gnomes littered the entrance at Mulberry.

"There's a whimsy to it, I think of freshness, I think of England, it feels very mature but very young at the same time," actress Gillian Anderson told Reuters backstage at the Mulberry show on Tuesday.

A closer look at Christopher Kane's futuristic candy-colored dresses revealed Perspex nuts and bolts holding the draping together, plastic ruffles and masking tape details.

"Christopher Kane is so inventive, every season feels brand new and like nothing else he has ever done before," Sarah Harris, fashion features editor of British Vogue, told Reuters, adding that the collection was "so clever."

Bright metallics added a futuristic flair to feminine silhouettes at Burberry Prorsum, where models strutted in saturated metallic coats, a twist on the classic Burberry trench coat, in fuschia pink, cobalt blue, bronzed golds and silvers, creating a rainbow palette on the runway.

Jonathan Saunders spun a twist on simple separates with metallic fabrics on pencil skirts and tailored dresses, while Holly Fulton added a naughty edge with pastel floral garments made from pvc.

While florals were a dominant motif amongst the collections, some designers moved towards more modern graphics. Paul Smith worked block geometric prints into a structured collection of separates, using darker hues of red, yellow and green, also seen at Roksanda Ilincic, where Mondrian-esque colors were incorporated into bold block curves on shift dresses.

Aztec and Mayan prints were at the center of Fyodor Golan's vivid collection, echoed by Matthew Williamson in a palette of blues and reds, while Peter Pilotto took tribal patterns to new levels, creating optical illusions with their monochromatic prints on layered separates and full-skirted dresses.

The fashion pack moves on to Milan on Wednesday before descending on Paris for the finale of the season.

(Reporting By Piya Sinha-Roy and Li-mei Hoang, Additional reporting by Joanne Nicholson, editing by Paul Casciato)