Sir Ranulph and his five-man team will cross the continent during winter over a six-month period. Going with them will be two machines to help carry their equipment.
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Butterflies and nerves of steel were behind the images shared and seen by millions across the globe.
The Duke and Duchess of Sussex thanked everyone who took part in the celebrations on Saturday, Kensington Palace said.
Established in 1913, the flower show has become one of the world’s biggest showcases for horticultural excellence.