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The royal matriarch was joined by several other members of her family. Prince Charles, a keen horticulturist, and his wife Camilla, Duchess of Cornwall looked delighted to be celebrating the world's most famous flower show. Charles, 64, eagerly chatted to many of the gardeners presenting their designs as the royal couple walked amid a sea of beautiful blooms.
Charles was also happy to share his considerable knowledge with his son, Prince Harry and was seen pointing out flowers and plants of interest as the royal party toured the exhibition.
It was a particularly poignant visit for Harry, who proudly showed his grandmother a garden very close to his heart. His own charity, Sentebale, is taking part in the world-renowned horticulture event for the very first time.
The Forget-Me-Not garden was created by renowned landscape designer Jinny Blom to reflect the Lesotho landscape and its people — and Harry was "passionately" involved in the design process, even having preliminary drawings sent over to him for approval while he was serving in Afghanistan.
The Prince, 28, is so committed to Sentebale, which he co-founded in 2006 to help vulnerable children in Lesotho, that hours after he arrived back in Britain after a six-tour US tour, he was by Ginny's side, discussing the garden.
At his request, the design also pays tribute to Harry's late mother, Princess Diana; the hearts and crown design engraved onto a circular terrace acting as a memorial to the beloved royal.
It was a busy day for Harry who had joined forces with his brother William that morning to open a new Help for Heroes centre in Wiltshire.
A rousing speech by RAF search and rescue helicopter pilot William officially opened the centre, which has the capacity to accommodate 50 residents, four families and over 150 day visitors.
Following his brother's speech, Harry waved the flag to symbolically open the Hero Ride, in the biggest cycling demonstration of national support for the wounded this country has ever seen.
The chance to enjoy a preview of the Chelsea Flower Show made Monday's event a star-studded affair. Gardening enthusiasts from Helen Mirren to Jamie Oliver, who was busy making pizzas for some of the visitors, attended the springtime show, as did Jerry Hall, Rob Brydon and Ben Fogle.
The Flower Show officially opens on Tuesday and will be open to the public for five days. To celebrate its landmark year, the ban has been lifted on garden gnomes; ordinarily gnomes and "other brightly-coloured mythical creatures" are not allowed.
More than 500 exhibitors have worked hard to present 15 show gardens, 19 smaller gardens and 150 exhibits to make up the 2013 show.