The Duchess of Cambridge was photographed out and a “boot” in London sporting a casual outfit paired with well-worn hiking boots she’s had for more than a decade, according to royal watchers.

The mother of three was embarking on her first official royal engagement since she went on maternity leave in March. She visited the Sayers Croft Forest School and Wildlife Garden in West London on Tuesday, to learn about a program that gives children in the city the opportunity to interact with nature.

In addition to a stylish grey sweater, olive green jacket, and brown skinny jeans, Kate wore a pair of Penelope Chilvers’ tassled boots that she’s been photographed wearing on numerous occasions.

The royal wore the boots during a hike in the Himalayas in April 2016, and again later that year when she visited Bella Bella, B.C. with her husband Prince William. Designer Penelope Chilvers’ told PEOPLE magazine in 2014 that she made the boots specially for the Duchess.

During her outing at the school on Tuesday, Kate was spotted smiling as she crouched down to look at spiders and other creatures in the garden with the school children.

Kate gave birth to her third child Prince Louis in April.