King Charles is set to become a “brilliant” monarch after serving the “longest apprenticeship in history”, the former prime minister has said. Mr Cameron revealed that when he was in power, he held audiences with the then Prince of Wales so that Charles could prepare for the day when, as sovereign, he would have weekly meetings with the prime minister. “I had audiences with Prince Charles when Queen Elizabeth II was on the throne because she wanted to start thinking about how to run those audiences,” Cameron told the BBC’s Sunday With Laura Kuensberg – in an interview to be broadcast on Sunday. “From what I’ve seen he’s going to be brilliant at this job. Great at listening, asking questions, giving sage advice and sage advice. This was probably the greatest apprenticeship in history.” She said that, like his mother, the new king was an “excellent diplomat” and predicted he would prove a “very worthy successor” when it came to supporting the British government of the day abroad. “I’ve seen him in action at Commonwealth Heads of Government meetings and he knows everyone personally, interacts with them brilliantly,” Cameron said. “The soft power that the British monarch brings to help a prime minister and a government with all these international relationships was obviously outstanding under Queen Elizabeth II. “I think you will find that Charles III will be a very worthy successor in that regard.” His comments were echoed by another former prime minister, Sir Tony Blair, who said the King was well prepared for what was to come. Writing in The Sunday Times, he said: “I feel for King Charles at this moment of heavy responsibility. But I also believe in him. “Strengthened by his mother’s example, his devotion to duty is clear. He is an intelligent, caring and good man. His sense of service to his people and his love for them will be as deep as hers. “Don’t imagine for a moment that in recent years he hasn’t watched, absorbed and thought about what it means to be king. He is well prepared and, I have no doubt, resilient for the task ahead of him.”