Prince Charles and his sons feature in a triple portrait in a set of Royal Mail stamps to mark his 70th birthday. Charles, along with Prince William and Prince Harry, were photographed during the July celebrations at Buckingham Palace that marked the RAF’s 100th anniversary. The Duke of Cambridge served as an RAF search and rescue helicopter pilot for a number of years, while the Duke of Sussex is honorary Air Commandant of RAF Honington. Charles himself is Marshal of the Royal Air Force – and the images show the heir to the throne at work and play in celebration of his milestone birthday on 14 November. Polo princes is the theme of another stamp, with William and Harry sharing a joke about their father during an event at Cirencester Park Polo Club in 2004, when they took part in the Gurkha Welfare Challenge Trophy. Charles’ Scottish retreat, the Castle of Mey, is the backdrop for a portrait of the prince on another stamp. A scene that shows the heir to the throne greeting schoolchildren during a visit to a Tudor manor house, Llancaiach Fawr Manor near Cardiff, has also been chosen for the collection. The final two stamps show an image of Charles hugging wife Camilla – which was used for a 2015 Christmas card – while the last is a photograph of the prince by himself. The six stamps are available to pre-order from the Royal Mail website and go on general sale from Thursday.