Her Majesty, 95, complained to the Duchess of Cornwall and Elin Jones, presiding officer of the Welsh Parliament, that the UK still had no idea who might be attending the COP26 conference, which is due to begin in Glasgow on October 31. It has been billed as a crucial point at which nations will have to commit to drastic measures to combat global warming.

       One of the few who has confirmed he will be there is US President Joe Biden. Russian President Vladimir Putin and Chinese premier Xi Jinping, leader of the world's biggest polluting nation, have still not committed to attending.

       The Queen, who was in Cardiff with Prince Charles and Camilla to attend the official opening of the sixth session of the Senedd, the country's devolved parliament, said: "Extraordinary isn't it...I've been hearing all about COP. Still don't know who is coming. No idea.

       "We only know about people who are not coming."

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       In remarks overheard on the Senedd's live feed, she appeared to talk about how many rooms had been reserved for delegates in Glasgow and whether they would be needed. "It's really irritating when they talk but they don't do," she said.

       Ms Jones agreed and referred to Prince William's criticism of space tourism in a BBC interview broadcast yesterday.

       "Exactly, it's a time for doing," she said. "And watching your grandson on the television this morning saying there's no point going to space. We need to save the Earth." The Queen smiled and said: "Yes, I read about it."

       Her frustration at world leaders echoed those of Charles, who complained in a TV interview this week about politicians failing to deliver on promises. "They just talk, and the problem is to get action on the ground," he said.