The queen and her eldest son were hosting a drinks party at the presidential San Anton Palace after the opening ceremony of the 2015 Commonwealth summit.
But the pair were left waiting for five minutes for some of the 10 new Commonwealth leaders attending, after most of them fell foul of heavy security measures which closed many roads.
"Are you sure they're here?" quipped Charles as the queen, dressed in an aqua-green coat and hat with pink flowers on it, peered around the entrance to the Grand Master's Hall where the reception was to be held.
Queen Elizabeth, who is the head of the 53-country strong Commonwealth, was in Malta along with her husband Prince Philip, Charles and his wife Camilla.