In October 1988 the Queen paid a state visit to Spain. Alighting from the aircraft in a blue and white silk dress and matching coat, she was greeted warmly by King Juan Carlos, who announced: “Darling, you look wonderful.”

With those four words Karl-Ludwig Rehse’s career was made. He was chosen to be one of Her Majesty’s three private couturiers, picking out materials and designing outfits for her for the next three decades.

Born into a middle-class family in 1937 in Essen, Germany, better known for its colliery than fashion, Karl-Ludwig was the middle son of three brothers. Their father, Ludwig, an engineer, died aged 40 of a heart attack, and they were raised by their mother, Ruth.

Transfixed by an Evening Dress

Yet it was Karl-Ludwig’s maternal grandmother who spotted and nurtured his artistic flair. During his youth she took him to a craft fair in Munich, where he became transfixed by an evening dress designed by John Cavanagh, an Englishman.

“And that was it!” Rehse told the Basler Zeitung. “I knew I wanted to create the same. That evening my grandmother called my mother and said, ‘We don’t need to worry about what the boy will do in future — he’s going to be a couturier!’ ”

However, in postwar Germany becoming a couturier was easier said than done, for it was frowned upon for men to design women’s dresses. Undaunted, Rehse set out to train as a gentlemen’s tailor. After his apprenticeship he moved to Munich and persuaded the authorities to allow him to complete a master’s degree in dress design, with Horst Kloess, known for his designs for film stars and nobility.

Rehse decided his next move should be to Paris, but only after a holiday to England. While in London he met the man who would become his lifelong partner, John Anderson, who could not speak a word of German at first, just as Rehse could not speak any English.

In postwar Germany becoming a couturier was easier said than done, for it was frowned upon for men to design women’s dresses. Undaunted, Rehse set out to train as a gentlemen’s tailor.

Anderson was a well-known stylist, preparing models for Cavanagh, who was by now designing outfits for the young Queen Elizabeth. Rehse initially got a job sewing for Cavanagh, and later worked for Bellville Sassoon and Norman Hartnell.

In 1988 Anderson left Cavanagh’s company and, with Rehse, set up his own boutique, John Anderson Couture, in Chiltern Street, Marylebone. It was a huge risk because haute couture was only affordable to a wealthy few and therefore hard to plan business models for. Within weeks, however, Buckingham Palace had called for the pair to present their summer collection to the Queen at Windsor Castle.

It was a success: 16 dresses were ordered for a state visit to Spain and they were given three weeks to complete the work. That was their first significant commission.

The Perfect Zip and Buttons

Over the years the pair became valued by the Queen as discreet designers who took meticulous care to find the perfect zip and buttons for the “perfect cloth”, which matched Phillip Somerville’s “perfect hat”. They understood that she must not be a slave to fashion and yet chic; also that, being of a diminutive stature, bright colours would help to pick her out in a crowd.

John Anderson Couture was granted the Royal Warrant in 1992 and two years later the Queen Mother’s Royal Warrant. In 1996, when Anderson died of cancer, it was the Queen’s personal endorsement of her favourite German designer that encouraged him to continue.

Although devastated at the loss of his partner, “Karl”, as the Queen knew him, threw himself into his work. He was awarded the Royal Warrant in 1997 for his persistence and thus embarked on a lengthy solo career, helped by the Spanish seamstress Teresa Sanz.

In Rehse’s studio, a sketch for a dress the Queen wore to the Chelsea Flower Show, 2006.

Over the years he came to know and like the corgis and their foibles, as well as the Queen’s favourite hues of blue and apple green. Yet Rehse never revealed a word of the intimate discussions behind the royal silkscreen, except to admit that he and the Queen had a similar sense of humour. So assimilated did he become, it was said that he began speaking German with an English accent.

Jean Phillips, a former couturier to the Palace, recalled attending Ascot with Rehse to see what the Queen was wearing, and how, like a small boy, he would hang over the rails to catch a glimpse, exclaiming delightedly: “That’s one of mine!”

The only time Rehse claimed to have been informed that the Queen would be wearing one of his outfits was in a call on New Year’s Eve in 1999, to say that Her Majesty would be wearing a dress and coat designed by him to the Millennium Party at the Dome.

Single Malts and the Greek Islands

While he modernised the Queen’s look over the years, her unchanging style meant that she could wear his outfits more than once, which, being of a naturally frugal disposition, she often did, he claimed, because otherwise “it is a waste”.

In 2000 he renamed the Marylebone shop Karl-Ludwig Couture and continued to design some of the Queen’s most memorable outfits, including the coat she wore to celebrate being the oldest reigning monarch and the pink-and-white flowered dress she wore to open the official red boxes for her portrait by Mary McCartney, which marked the same occasion.

In his spare time Rehse enjoyed single-malt whisky — like the Queen — and going on cruises off the Greek islands.

Seven years ago his allegiance was rewarded when he was made president of the Royal Warrant Holders. However, his proudest moment came in 2015, when the Queen made him an honorary member of the Royal Victorian Order, the highest honour given to those who have served the monarch personally.

Karl-Ludwig Rehse was born on October 12, 1937. He died of a heart attack on May 12, 2019, aged 81.