When Jean Muir died 10 years ago it seemed her fashion label would surely perish with her, thanks to her husband, her loyal staff and a band of famous groupies, the house is flourishing anew.

By Drusilla Beyfus. Photographs by Ellen Nolan Jean Muir was so much her label that when she died of cancer in 1995 it seemed unthinkable that the dress business she founded in the 1960s had much of a future. Her rigorous Scottish individualism, her all-embracing ethos about dressmaking, and the way in which she personified her designs appeared to defy a follow-up. Yet through a series of unpredictable events and canny business moves, the label is emerging from the shadows. Harry Leuckert, who married Muir in 1955 and is co-founder of the business, explained the position when we met in London recently. The loss of Jean and the increasing demands of trading had pointed to the logic of shutting up shop. As he put it, 'When I told the staff that I had decided to close the business they came back and said, "Please give us a chance. We can do it." And that was how it happened.' Two other options had been rejected out of hand by him, namely to sell the company - 'Never, ever!'- or to hand over to a known designer to carry on the label. One poignant fact worked in favour of continuity. Looking back. Leuckert believes that the in-house team were strengthened during the final months of Muir's illness when they had to learn to manage without the designer's usual total involvement.'It was a form of trial period for what awaited.'

After a period of uncertainty, the continuing collections evoked an almost audible sigh of relief from Muir's well-known loyalists. The theatre dames Diana Rigg and Judi Dench wear Jean Muir both on and off the boards. Julie Walters chose the label for her appearance at the Billy Elliot film premiere (and wore a Muir design in BBC2's modern-dress Chaucer production The Wife of Bath) on the basis that, 'Jean Muir is beautifully cut, simple, flattering and elegant.' As Lady Antonia Fraser once put it, 'A number of women who have to define themselves in public by their appearance... turn to her clothes with ecstasy and relief.'

Rachael Stirling, Diana Rigg's actress daughter, says she puts on Jean Muir when her role is to look glamorous. Stella McCartney is known to slip into vintage Muir from time to time. When Sienna Miller was required to hit a 1960s sartorial note yet retain her Notting Hillbilly bohemian aura in the movie Alfle, it was a Jean Muir that came to the rescue. And it's to the point that the former long-serving editor of Vogue, Beatrix Miller, shares an admiration for the designer with the present editor, Alexandra Shulman. The creative reach of the label is interesting, too - some of the reigning younger names in fashion, such as Hussein Chalayan, are influenced by Muir's ideas while several have commented on an affinity between the designer and the hugely successful (and hugely copied) Marc Jacobs.

However, what wearers really go for is that Jean Muir is essentially a long-life product. Joanna Lumley, an undisguised Muir groupie, picks up on that aspect in her recently published autobiography, No Room for Secrets: 'Over the years I collected them and wore them again and again. There is a huge suitcase full of Jean Muirs in the spare room.., so that one day I can get them out and wear them as retro chic. Not so retro either, many look as beautiful now as they did then.' Lumley's experience is shared by the former house model Tamsin de Roemer, now a fashion designer in her own right, who says she still wears a jacket made by her mentor in the mid -1990s, which she teams with jeans, boots and a T-shirt. 'I also have two cashmeres with holes, which I can't resist wearing.'

Clients old and new rallied, but the business side took a nasty knock or two in the post-Jean era. The United States market, which accounted for a third of the annual £3 million turnover for Jean Muir Ltd. dropped out of the calculation on the death of its namesake. And Muir's formerly much sought-after and lauded minimalist outfits at Bergdorf and Bloomingdales lost their place in the spotlight. Worse was to follow. Jaeger, with its three main outlets in King's Road, Regent Street and Knightsbridge, and which had stocked Jean Muir prominently since 1989. decided to pull out of its contract with the business. The deal was worth between 40 and 50 per cent of the company's turnover. 'The then new-broom management of Jaeger decided there was no room for two labels in the company,' Leuckert recalled. Furthermore, Selfridges, in a draconian edit of its regular stockists, dropped the label. Seeking new retail territory, the house approached Harrods but I as Leuckert said, 'We got nowhere.'

A response from base camp was overdue. This took the form of expansion, retrenchment and restructuring. Plans were made with the knowledge that, despite the loss of sales in certain outlets, various factors had conspired to keep the turnover stable at £3 million, with one exception. 'Nineteen ninety-six was a bad year but 1997 was a boom year in which our turnover increased from £3 million to £3.6 million.' the newly appointed managing director, German-born 28-year-old Nicolas Steineke, told me. 'Perhaps our customers thought it was the last chance to buy Jean Muir. Now the figure has settled again at about £3 million.'

Opening a shop with its own front door represented the big push forward, a move long on Muir's wish list. The project was realised at Conduit Street last summer, with new neighbours including Vivienne Westwood and the earnestly hip B Store. Simultaneously, a decision was taken that the business would move out of the elegant showrooms at Bruton Street which it has occupied since 1955, at a date yet to be finalised. So it will be goodbye to memory lane, with recollections of innumerable collections launched amid bowers of fresh white flowers, at the finales of which the diminutive figure of Muir would appear, clad in her virtual house livery of navy blue - whatever the shades launched on the runway. 'Bruton Street has become an irrelevance. It's over and we must move forward,' Leuckert said firmly. The plan is for Conduit Street to become the company HQ, incorporating the retail shop, the wholesale showrooms and the offices. The design team - of whom more later work out of Clerkenwell.

Jean Muir's spirit stalks the shop. Customers enter through a monumental, minimalist glass door which is a beautiful artefact in its own right. The all-white space (1,800 sq ft) has the air of a swish art gallery. Flooring is of Tessos marble, and the use of mirrors and burnished steel in the decor together with a rarity in the neighbourhood, a flood of natural light, makes it all seem a bright harbour. Yet it is a selling place. first and foremost. The sizing range of the collections has been extended to include sizes 16 and 18, though customers may have to ask for these as they are sometimes not put out. Pricepoints are at the lower end of international designer label merchandise, but the word lower in this context is relative. Examples are a cashmere and silk sweater, from £335, a satin button-through dress, £630; a tweed top coat, from £775; an Orient brocade coat, £995; a nappa leather jacket. from £1,080.

Leuckert is particularly keen on his insistence on upping the standard of customer service to the extent of offering shoppers a drop of restorative hospitality. He tells the story of the time when he had to deal with a totally shopped-out husband who was accompanying a wife clearly in for a long haul at the shop. He suggested tea, coffee, both politely refused, but when he came up with the offer of something stronger plus the daily papers and a comfy chair, that was nearer the mark. 'The husband told me, "This is so much nicer than being dragged round Selfridges", and paid up for his wife's indulgence with a smile.'

'We opened without any razzmatazz and the shop has been a success from day one.' Leuckert added. Costs have been self-financed without need to borrow capital. On present form, the venture has worked well enough for the company to be talking about a second 'stand-alone' shop. 'The Conduit Street shop will compensate us for the Jaeger losses,' Nicolas Steineke said. 'Jaeger did express an interest in a further dialogue but by then we had opened our shop.' The broader retail picture has perked up considerably. Selfridges is stocking the spring/summer collection in a 'dedicated space'. Anna Garner. head of fashion at Seifridges. says, 'We didn't do justice to Jean Muir before. The modern atmosphere of their new shop is what we like and how we want to present her.' Harrods has come in as well.

Quite how this high-end fashion house works on the creative side without a leader is a mystery best explained by the belief that ghosts can deliver. Technically, the task of putting together a new collection is done by an in-house team of four women who were trained by Muir and who have virtually osmosed her thinking and are adept in her methods. I met the disciples where the designing gets done at the company's Clerkenwell premises and found them in mid-preparation for the autumn/winter '05 collection. Broadly, responsibilities divide along the following lines, allowing for the fact that much stress is laid on mutual discussion and consensus. Joyce Fenton is chief designer. Angela Gill does knitwear. Caroline Angell is pattern cutter and toiliste (she first cuts the cotton toile and then repeats the shape in the form of a paper pattern to send to the manufacturer). Sinty Stemp, who has been with the cornpany for 17 years, is the fourth member. She read history at university, is now head of wholesale, and deals with the store buyers who keep the label's order book in good nick.

Jean Muir's sketchbooks and samples from past collections are a fund of inspiration, but the team balk at any implication that they do copies. Their take on the matter is that the skill lies in adapting and interpreting such Jean Muir lines that are relevant to what's going on now. And who decides on that. I asked. We were back to discussion and consensus. A small clue on the matter came from Stemp.' We always ask whether we would wear a proposed shape or pattern ourselves. Our personal view does count. We will also bear in mind what a particular store buyer might do well with.'

'We are not a label about a label,' she elaborated. 'Miss Muir would never do a theme collection or say we are going to do a pirate collection. We make clothes for an individual. If Jean Muir had a muse it was the female body. Her clothes always have an element of femininity.'

Joyce Fenton explained. 'Miss Muir had a signature way of making clothes and we try to follow that. For example, our jersey dresses are made by one person, on one machine and the dress will have top stitching [a needlecraft skill].' Stemp chimed in with the observation that it takes the manufacturer several days to make one of their jersey dresses.

I watched the Muir collective working with a 'storyboard' for colours and fabrics for the next collection. The board displayed scraps of materials in different weights. weaves, colours, patterns. Snippets of vintage Jean Muir fabrics sat beside pieces of currently fashionable brocade; there was tweed woven with as many as half a dozen different types of thread, including one combining wool and ribbon. Fenton was choosing a mixture of materials as a guideline to send to the fabric makers to interpret.

Working closely with the label's suppliers remains a linchpin of the production process for the team. They like to work with people who know their standards, Fenton said pointedly. Linton Tweeds of Carlisle is a specialist weaver that supplies fabric for the house, a connection that has lasted for 25 years. Linton has its own facilities for dyeing, and makes one-offs and exclusives for Jean Muir, and also for Chanel. The Muir team will submit the sample fabrics I saw being selected and the Linton team consisting of a design director, Robert Irvine, and two designers - will work on the Muir suggestions and come back with their realisation. If need be, the two teams keep going with revises until they come up with the answer.

In addition to the new stuff, the vogue for vintage detail has done its bit towards sustaining the reputation of the label. 'Sometimes we will get out some vintage designs and are reminded of something special such as beautiful beading or a detail and incorporate that,' Stemp said. The market for old pieces seems limited only by a shortage of product. Fiona Stuart, a partner in the west London shop Rellik, a hunting ground for the likes of Kate Moss, says, Original buyers hang on to Jean Muir for dear life. Our customers like the 1970s and 1980s styles when we can get them, and the 1960s too, but those are the rarest of all.' Prices at Rellik are in the low hundreds.

Aspects of the saga suggest an application beyond this specialised luxe company. A small-scale, tightly run ship can retain its identity among the giants in retailing (Jean Muir has only 20 full-time employees on the books). A policy of doing what you do best and leaving the rest to the others may be more effective than diversifying. Clothes that reveal their best qualities to the wearer but which don't always do justice to themselves in fashion photography have a place in the pantheon. As to the over-arching onsideration of the wisdom of running a creative house without the living hand of a leading designer, the jury is out on the long term. But, to date, it appears that a good reputation is an abstract replacement.

However, it would be unjust to describe Harry Leuckert as an abstract force. Born to German parents, he has emerged from self-imposed shadows over the years. Declaring that he feels 'tremendously positive', he has jumped to it in a manner that is not wholly in character for a man who openly avows a preference for the 'gone fishing' option. His affection for retreating to his country house in Northumberland with its garden and access to fishing rights and a shoot, his finca in Spain, and the absence of mobile phones and e-mails in his daily routine have done little to unseat that image. But in practice the updated Leuckert is closely involved in the present phase of the company. along with his new family. His daughter, Friederika, is running the Conduit Street shop; she is married to Nicolas Steineke. Leuckert has married the mother of his daughter. Within the intense partnership of his former marriage, it was no secret that Harry had his own life and interests. He spoke to me of Jean like this: 'We loved each other very much. We were very close emotionally and creatively.' Few will doubt he has done right by her to keep the legend alive and kicking.