Go big or go home: that is the new party dress code. Forget the little black dress, and get ready for the grand gown. When Erdem x HM drops on 2 November, the smart money will be snapping up a £149 party dress with intricate snowdrop embroidery on formal stiff jacquard, embellished with a traditional grosgrain bow and falling from a precisely gathered waist into a voluminous, ankle-length tiered skirt.

The November issue of British Vogue features Claire Foy in a floor-sweeping, dusty-pink ballgown by Christian Siriano. As the star of Netflix drama The Crown, Foy is no stranger to a ballgown. The Crown, Downton Abbey, the Queen’s 90thbirthday last year, Gucci’s sponsorship of an exhibition of English aristocratic style at Chatsworth House and the resurgence of Princess Diana as a style iconthat has accompanied the 20th anniversary of her death are combining to revive the ballgown, a style of dress that until recently seemed as anachronistic to modern entertaining as the bouillon spoon.

The snowdrop-embroidered ballgown is one of the standout showpieces of Erdem x HM, this year’s most eagerly awaited designer/high street collaboration, which goes on sale next month. Erdem Moralioglu was born in Canada to a Turkish father and British mother, moved from Montreal to Birmingham as a child and founded the Erdem label in 2005. In the past four years, Moralioglu has been awarded three top gongs at the British Fashion awards – red carpet designer of the year, womenswear designer and establishment designer – and has expanded his business from a space in Hackney, north-east London, to a Mayfair boutique and headquarters.

This is the first time in eight years that H&M has partnered with a British fashion designer for its collaboration. In 2009, Matthew Williamson used the platform to fly the flag for the boho-chic style of loose muslin, kaftan shapes and hummingbird motifs then in vogue. The hype that surrounds the H&M collaboration increases every year – in 2015, jackets from the Balmain x HM collection were resold on eBay at 10 times their retail value, making them as expensive as real Balmain. It will bring the global spotlight back to British fashion this autumn, and bring into focus the new generation’s appetite for formal partywear. That Erdem is a consistent favourite wardrobe of the Duchess of Cambridge can only fuel the fervour.

The ballgown craze about to wow the high street has already swept the red carpet. Dresses with stiff, outsized skirts designed for airy ballrooms rather than crowded dancefloors have become de rigueur at the Met Gala, presided over by Anna Wintour and dubbed the fashion Oscars for the cut-throat competition on the red carpet. Actor Lena Dunham’s Elizabeth Kennedy dress and Rihanna’s infamous imperial-yellow mega-gown pointed at a trend for grand, formal dresses that was winning unlikely fans among independent-minded, modern young women.

Moraliogliu dressedFoy in a jacquard dress with courtly squared-off train at the most recent Met Gala. The designer’s fascination with the Queen was celebrated in the recent London fashion week show for his mainline collection, inspired by a meeting in 1958 between the Queen and jazz pianist Duke Ellington. His buttercup-yellow satin dress with ribbon epaulettes, a deep V-neckline and full, floral embroidered skirt, worn with long silk gloves, had a similar silhouette and mood to the high street equivalent that features in the H&M collection.

The Erdem x HM collection includes casual pieces, such as a logo-emblazoned grey hoodie for £49.99 and, in the designer’s first ever menswear pieces, a floral-printed army-green nylon rucksack. But the most intense competition among shoppers will be for the highest-priced pieces, which are produced in very limited numbers. The snowdrop ballgown and a multicoloured, floral-print jacquard dress with a high halter neckline, which will sell for £119.99, are likely to have stock of only 10 or 20 each per store. The high quality of the fabric, the workmanship of the embroidery and the elaborate construction of these dresses make them highly sought-after by fans of designer fashion priced out of Bond Street. While the quality is by no means equivalent to the dresses available in Erdem’s mainline store, the price tag constitutes a bargain compared with the £2,600 for which an Erdem jacquard evening dress sells.

Instead of totes or bumbags, the two handbags in the Erdem x HM collection are snap-fastening, faux-crocodile structured handbags of a type instantly recognisable from images of royal engagements over the past half-century. Princess Margaret, as photographed in fur coats on the arm of Lord Snowdon in the 1960s, is the icon conjured up by a leopard-print faux-fur coat for £149.99, with silk ribbon trim, patch pockets and the Erdem logo embossed on to its outsized gold press studs, which is set to be another highly prized item when the H&M collection goes on sale.Read more at:http://www.sheindressau.com/tea-length-wedding-dresses-au | http://www.sheindressau.com/casual-wedding-dresses