Designers by royal appointment
LONDON, England (CNN) -- Designing clothes for as high profile a figure as Britain's Queen Elizabeth II is one of the greatest challenges the fashion world has to offer.
For a couturier it is the chance to create outfits for a woman who is photographed everywhere she goes and is rarely spotted in the same ensemble twice.
But that also means ensuring she looks her best whether attending a state banquet with world leaders or touring a factory and creating styles that blend contemporary fashions with the timeless elegance and tradition of the monarchy.
Couture designer Stewart Parvin recalls the secretive selection process that took place before he started working for the queen four years ago.
"At first I wasn't told who it was for," Parvin told CNN.
"It was, 'Could you design for someone who is a really prominent person in the public eye and wants a very chic image?' I thought it was going to be a politician or a tycoon's wife. I put together a packet of sketches but it wasn't until they were chosen I knew who they were for."
Since then, the queen has worn Parvin's designs for public occasions such as last year's celebrations marking the centenary of the Anglo-French Entente Cordiale.
"She is someone who is very interested in her clothes. She always has an opinion on it and she has a very informed opinion and she knows when its right and she knows when its wrong," said Parvin.
Couture designer Karl-Ludwig Rehse, who has received royal warrants for his work with both Elizabeth II and the late Queen Mother, describes the queen's clothes as a work uniform.
"They have to be comfortable in as much as when the queen puts on the clothes she wants to forget about them," he told CNN.
"You have to take into account the different countries and the different climates in which they'll be worn. The queen always makes sure that she follows the tradition."
While most people would be hard pressed to imagine what they will be wearing the next day, the queen's wardrobe is planned out months in advance, says Rehse.
"It's not the case that the queen is going somewhere next week and thinks 'What am I going to wear?' Sometimes it is six months, 12 months or longer."
Both Parvin and Rehse involve the queen in the design process, culminating with fittings at Buckingham Palace.
"Sometimes I choose the fabric and then propose ideas for them, as I would do for any client," said Parvin. "I put together a scheme, maybe four designs for one fabric combination then she would look at them and either choose a design straight away or suggest some changes."
Rehse says the queen asks him to come up with two or three different alternatives for a particular fabric she likes before settling on a final design.
"I do get a lot of input from the queen," said Rehse. "The pressure is there but I take great joy out of it and it's very rewarding to see Her Majesty wearing my clothes in public."
Milliner Philip Somerville received a royal warrant following 12 years working for the queen. Now, when the queen steps out she's usually wearing a Somerville creation.
"You have to realize that you are never sure when Her Majesty will wear [a particular hat]," he said. "It depends on the weather on many occasions. You are also creating something that has to be very wearable and must be in colors that suit her. She must be noticed in a crowd."
After 33 years in business, Somerville is handing over the reins of his company to Dillon Wallwork. And while, providing hats for one of the world's most famous heads might be a daunting challenge, Wallwork says it is one he feels ready to take on.
"I've been here for some time now and we've always had a Philip Somerville look which is very clean, understated and elegant," said Wallwork.
"You know you are under a certain pressure because of the press and what people are going to say. You know she is going to be looked at. There are certain styles that you can and can't do but within those limits there's lots that you can do. It's quite a challenge but the queen can be quite adventurous."