Kate, 41, who helped design a Chelsea Flower Show garden in 2019 to encourage the public to reconnect with nature, chatted to young picnickers at the site's bandstand.

The pupils were from 10 schools participating in the Royal Horticultural Society's (RHS) campaign for school gardening, and were invited to an outdoor lunch ahead of the launch of the organisation's world-famous annual event in London.

The picnic initiative is aimed at introducing gardening and nature to more children - something the princess has championed.

Kate, who recycled a silk pink ME+EM shirt dress for her unannounced appearance at the event on Monday, inspired the idea during a conversation with the RHS in 2019 when she co-designed her own garden, Back To Nature, for the event.

The royal, whose family consists of Prince George, nine, Princess Charlotte, eight, and Prince Louis, five, along with husband Prince William, felt more children should be involved in the Chelsea Flower Show.

Kate's garden showcased the benefits of the natural world and what it can bring to physical and mental well-being.

At the time, Kensington Palace said the woodland wilderness garden - designed alongside landscape architects Adam White and Andree Davies and the RHS - would "inspire families to get outside and explore nature together".

The royal is following in the footsteps of her father-in-law the King, who when he was Prince of Wales was known to have a passion for horticulture.