Oscar de la Renta's passing has left a vacancy for couturier to America's royalty

He excelled at polite clothes with a touch of pizzazz

Designer Oscar de la Renta takes a bow after showing his Spring 2015 collection in September, his last show before his death (AP)

Following the death of Oscar de la Renta late on Monday, many have focused on his position as designer of fairytale evening dresses for glittering socialites and red carpet tromping. Which was, of course, important. It helped to cement de la Renta's name in the general public consciousness, via gossip pages, television news coverage and Sex And The City episodes. Oscar de la Renta dressed Hollywood royalty and international aristocracy, leading ladies and First Ladies - most recently, Michelle Obama, who wore her first De La Renta just over a week ago.

Nevertheless, all of the above focuses attention on who the man dressed, rather than what he dressed them in. True, the bold-faced names and instantly-recognisable faces probably helped propel De La Renta's business to its current state, making close to £100m in sales annually. It also diversified into fragrance, accessories and home decor as well as the core ready-to-wear business. But if de la Renta wasn't making decent clothes, all that celebrity froth wouldn't have counted for anything.

What Oscar de la Renta excelled at was making polite clothes with a touch of pizzaz - the word dreamed up by former American Vogue editor-in-chief Diana Vreeland, who encouraged de la Renta to join the salons of Elizabeth Arden as designer to help make his name. That was in 1963 - by 1965, he had his own label.

Oscar de la Renta was born in the high society of the Dominican Republic to a Spanish mother. Despite frequently being pegged as a quintessentially American couturier, there was always a root of Old World craftsmanship in his clothing - he trained with Cristobal Balenciaga and at the house of Lanvin, and turned down a job with Christian Dior. In the nineties, he took up haute couture duties at the house of Balmain for nine years until the label decided to shutter the line, showing biannual collections in Paris. There are few designers working in fashion today who can boast a comparable pedigree.

On 13 October, the British designer Peter Copping was named as creative director with the intention of working alongside and reporting to the company's chief executive Alex Bolen as well as de la Renta himself. Copping's delicate, feminine style, intricately worked but simple in silhouette, are a contemporary counterpart.

Oscar de la Renta's style was most frequently described as classic. His clothes were always well-made and well-behaved, frequently beautiful. The spring/summer 2015 collection, his last, showed soft lace suits and pastel silk faille dresses with foliate embroideries, skirts cut higher in front to allow the legs to move easily, a de la Renta classic which was also a trademark of Balenciaga. He outfitted his women for every facet of their day, from day-suits to cocktail wear to gowns for the grandest social occasions.

Occasions like inaugural balls - Oscar de la Renta was an unofficial, unwritten White House uniform of sorts, thanks to his close associations with both Nancy Reagan and Hilary Clinton. Far removed from the vagaries of mere Hollywood endorsement, that kind of approval is the American equivalent of a royal warrant. De la Renta practically monopolised it.