"It was perfect. I thought it was very contemporary for her to do that," Grant told AAP on the phone from his studio in Paris.

"Royals don't often do it (repeat outfits) but it's great to see because they have so many events. Every day they have something to be dressed for, they cannot be just wearing things once."

Grant has been committed to 'slow fashion' before the buzzword even existed, launching his first ready-to-wear collection at the age of 16 while living in Melbourne.

He moved to London, then Paris about 25 years ago and relaunched his eponymous label at a fashion show in the Marais district, during which supermodel Naomi Campbell made a surprise appearance.

Grant describes mass-produced, fast-fashion as the "antithesis" to his finely cut, classic-lined signature dresses, coats and suiting, which are designed to be worn again and again.

"I grew up with pieces handed down from mothers, grandmothers, great-grandmothers," he said.

"I like that idea that things can last for more than a season, both in terms of style and ecologically."

Grant hit the headlines last year when Markle wore his trench and two yet-to-be-released dresses during the royal tour of the Pacific, prompting international department stores like Barneys and Moda Operandi to increase their orders.

But Markle isn't the first royal he's dressed - he counts the wife of former Emir of Qatar Sheikha Moza and Queen Rania of Jordan as clients, as well as American royalty the late 'Princess' Lee Radziwill.

His latest autumn-winter collection will be unveiled at Melbourne Fashion Week's opening runway show at the city's Town Hall on Friday, which celebrates 25 years of the fashion event.

While he won't be attending - it's buying season in Paris - his mum will be front row.

"She will be reporting back - even during the shows she sends me photos," he said.

*Melbourne Fashion Week runs from August 28 to September 5

Australian Associated Press