A professional lip reader has offered one theory about what King Charles was saying when he was caught on camera speaking in what appeared to be a frustrated fashion while waiting for his coronation to commence.

In scenes beamed live to viewers around the world, Charles was seen sitting in his coach alongside Camilla, waiting for the all-clear to enter Westminster Abbey to begin the coronation ceremony.

William and Kate, the Prince and Princess of Wales – accompanied by their children Princess Charlotte and Prince Louis – arrived late to the ceremony, and were forced to join the procession behind King Charles rather than entering Westminster Abbey before him, along with the rest of the royals and hundreds of guests.

As he and Camilla sat awkwardly in their carriage for several minutes, waiting for the OK to enter the Abbey, it appears Charles vented his frustrations – at least, according to two lip readers who independently viewed the footage.

“I’m worried about time, I mean it’s been longer this time and, well, erm, I mean look! I know,” a lip reader told the Daily Mail Charles said in one clip, which has been viewed several million times on social media.

“We can never be on time. Yes, I’m … this is a negative. There’s always something,” another lip reader told the Daily Mail they believed Charles said in the same footage.

Kensington Palace yesterday released a polished behind-the-scenes video to social media of William, Kate and their children getting ready for the weekend’s coronation – with footage showing the family racing to a waiting vehicle to make it to the ceremony.

Charles’ brief ill-tempered moments have made headlines since his mother’s death last year – most notably, two separate incidents caught on camera, one in which he signaled at an aide through gritted teeth to clear his desk, and another in which he fumed over a faulty pen while signing important documents.

And at the coronation concert, another off-the-cuff Charles moment was caught on camera. 

Downton Abbey actor Hugh Bonneville hosted formalities, and opened with a hilarious monologue that, at one point, triggered a rather awkward reaction from Charles.

The UK star started his speech by congratulating the newly crowned King and Queen, before paying tribute to Charles’ love of the arts.

“He himself is a painter, an artist … The artist formerly known as prince,” Boneville said, in reference to the late music legend.

Charles, 74, let out a burst of laughter before grimacing at the witty line.