LONDON, ENGLAND - JULY 12: Camilla, Duchess of Cornwall chats to Robert Hardman as she hosts the 30th Anniversary Garden Party for the National Osteoporosis Society in St James Palace on July 12, 2016 in London, England. Due to inclement weather the event was moved indoors. The Duchess of Cornwall has been connected with the charity for nearly 30 years. (Photo by Chris Jackson/Getty Images)

LONDON, ENGLAND - JULY 12: Camilla, Duchess of Cornwall chats to Susan Hampshire as she hosts the 30th Anniversary Garden Party for the National Osteoporosis Society in St James Palace on July 12, 2016 in London, England. Due to inclement weather the event was moved indoors. The Duchess of Cornwall has been connected with the charity for nearly 30 years. (Photo by Chris Jackson/Getty Images)

LONDON, ENGLAND - JULY 12: Camilla, Duchess of Cornwall laughs with her daughter Laura Lopes and Annabel Elliot as she hosts the 30th Anniversary Garden Party for the National Osteoporosis Society in St James Palace on July 12, 2016 in London, England. Due to inclement weather the event was moved indoors. The Duchess of Cornwall has been connected with the charity for nearly 30 years. (Photo by Chris Jackson/Getty Images)

LONDON, ENGLAND - JULY 12: Camilla, Duchess of Cornwall chats to actress Felicity Kendal as she hosts the 30th Anniversary Garden Party for the National Osteoporosis Society in St James Palace on July 12, 2016 in London, England. Due to inclement weather the event was moved indoors. The Duchess of Cornwall has been connected with the charity for nearly 30 years. (Photo by Chris Jackson/Getty Images)

LONDON, ENGLAND - JULY 12: Camilla, Duchess of Cornwall laughs as she hosts the 30th Anniversary Garden Party for the National Osteoporosis Society in St James Palace on July 12, 2016 in London, England. Due to inclement weather the event was moved indoors. The Duchess of Cornwall has been connected with the charity for nearly 30 years. (Photo by Chris Jackson/Getty Images)

LONDON, ENGLAND - JULY 12: Camilla, Duchess of Cornwall laughs as she hosts the 30th Anniversary Garden Party for the National Osteoporosis Society in St James Palace on July 12, 2016 in London, England. Due to inclement weather the event was moved indoors. The Duchess of Cornwall has been connected with the charity for nearly 30 years. (Photo by Chris Jackson/Getty Images)

LONDON, ENGLAND - JULY 12: Camilla, Duchess of Cornwall with Professor David Marsh as she presents the Professor with the Duchess of Cornwall Award for Outstanding Contribution to the field of Osteoporosis as she hosts the 30th Anniversary Gigarden Party for the National Osteoporosis Society in St James Palace on July 12, 2016 in London, England. Due to inclement weather the event was moved indoors. The Duchess of Cornwall has been connected with the charity for nearly 30 years. (Photo by Chris Jackson/Getty Images)

Boeing F/A-18 Super Hornet, a twin-engine, supersonic, all weather multirole fighter takes part in a flying display at the Farnborough Airshow, south west of London, on July 12, 2016. / AFP PHOTO / ADRIAN DENNISADRIAN DENNIS/AFP/Getty Images