It's long been called the "Canadian tuxedo", but Meghan Markle – who spent many years of her working life in Toronto, incidentally – proves that wearing double denim can look as refined and elegant as a cleanly tailored suit. 

The Duchess of Sussex and former Suits actress looked effortlessly cool and casual as she stepped out with her husband Prince Harry to take part in a gardening project with a Los Angeles-based preschool. 

The couple got stuck in helping the children sow seeds and work the garden as part of the event organised by the Assistance League of Los Angeles. It was no doubt an emotional day for the couple, as their engagement coincided with the anniversary of Harry's mother, Princess Diana's death. 

To mark the occasion, the couple planted forget-me-nots, allegedly the late Princess's favourite flower. 

To some onlookers, Meghan's outfit was a nod to her deceased mother-in-law, as the double denim look was a firm favourite of Diana's, especially when carrying out more casual engagements or spending family time with her sons. 

Meghan's take was decidedly sophisticated as she chose a stunning light wash denim shirt by Anthropologie, featuring a light stripe and contrasting cuffs. Worn tucked into her jeans and rolled to the elbow, it was the perfect match for her deep blue skinny jeans. 

The Duchess paired her outfit with simple black pointed toe ballerina pumps, and the all-important protective face mask, this time a simple blue one. 

She wore her hair pulled up off her face into a low knotted bun, looking neat and chic, while her makeup was simple and fresh. With just a gold bangle on her wrist and her usual rings, her look was utterly understated. 

Prince Harry, meanwhile, looked similarly casual in a navy polo shirt, blue jeans and worn light tan boots.