Jean Muir didn't invent the little black dress, but she made it her own. The trailblazing designer, who established her own label Jane & Jane in 1962 before branching out under her own name in 1966, was loved not for her catwalk extravagance or her look-at-me flamboyance, but for her no-nonsense elegance. Her clothes flattered the wearer, which is why so many women found her irresistible.

Antonia Fraser, Patricia Hodge, Bridget Riley and Joanna Lumley (who joined her as a house model in 1966) were among the fans of a woman who regarded herself as a dressmaker pursuing a craft, not a flighty fashion designer. 'She wanted clothes that people could wear every day,' says Kristina Stankovski, curator of a major survey of Muir's output at Edinburgh's National Museum of Scotland. 'She made clothes that made women look and feel their best. She had a very keen sense of how things would fit on the body.'

Ten years after Muir's death in 1995, her widower and business partner Harry Leukert bequeathed her archive to the NMS. To call it a substantial collection is an injustice. The 18,000 items are the largest holding of the work of a single designer anywhere in the world. That it has ended up in Edinburgh is a testament to Muir's life-long fondness for Scotland. Although born in London, she was proud of her Scottish ancestry which, coupled with her austere manner, is why they used to call her the Miss Jean Brodie of design.

'She always felt her Scottish ancestry was of great importance to who she was,' says Stankovski. 'Her knitwear was always produced in Scotland. Her yarns were specially dyed to her colour specifications.'

This first exhibition to be drawn from the archive seeks to give a behind-the-scenes look at Muir's professional life. It outlines every step of the design process by way of sketches, trial garments, finished dresses, accessories and photographs, not to mention several contributions from Lumley, who will be in town for the launch. 'It has been designed to show highlights of the collection and provide an overview of Jean Muir's remarkable career achievements,' says Stankovski. 'We talk people through the creation of the garment from the initial idea to the finished piece. We have a range of quite fascinating things, such as sketches, colour tests and fabric samples, that are rarely preserved by designers.'

Not surprisingly, it's all the curator can do not to slip into one of the exhibits herself. 'They're all very gorgeous,' she laughs. 'I wish it were my wardrobe.'

Jean Muir: A Fashion Icon, National Museum of Scotland, Edinburgh, Fri 7 Nov-Sun 15 Mar.