The now 70-year-old royal was asked how he was feeling, to which he replied: "How am I feeling? Older, older."
Charles and the Duchess of Cornwall were travelling to Spencer House - the former home of Diana, Princess of Wales' family to meet 70 special Septuagenarians who are volunteers actively involved with a number of royal couple's charities including the Prince's Trust, the Silver Line, Maggie's and Barnardo's at a party organised by The Sun.
The Spencer family last lived in the 18th century London mansion in the 1920s and today it is leased to the investment company RIT Capital Partners, chaired by Lord Rothschild, which has renovated the property.
Outside the event, Charles was handed the balloon and a £5.99 bottle of "Hot Nuts" grey squirrel repellent in a bag by the Daily Mail's Rebecca English, along with her fellow royal correspondents Hannah Furness and Valentine Low.
The Prince of Wales laughed and joked: "Where do you find these terrible things?!"
In honour of the Princes' 70th birthday, the Royal Family released two new portraits of the future monarch with his family.
Grace BackGrace is the Digital Content Editor at New Idea. Grace is a lifestyle junkie who has previously interned at Dolly, Stellar and marie claire, as well having written in the fashion and beauty sections at Finder.com.au. When not working, you can find Grace heading for the slopes, playing with her pup or stuck in a seemingly endless Instagram scroll.