Royal author Gyles Brandreth has called the Duchess of Sussex’s demonstration of her curtsy to the Queen “mocking” and “embarrassing”.

The writer and broadcaster told Vanessa Feltz’s Drivetime show on TalkTV: “Nobody curtsies to the Queen like that, and nobody would have advised her to do it that way.”

In the Sussexes’ Netflix documentary, Meghan, who was sitting on a sofa as the Duke of Sussex looked on beside her, put her arms out wide and bowed her head down low as she recounted how she tried to greet the late monarch when they first met.

Brandreth, a friend of the royal family, said the King was unlikely to watch the docuseries as he does not spend much time tuning in to television, but that the show was “interesting” rather than “explosive”.

He said of the curtsy: “It’s embarrassing, because it is mocking – and nobody curtsies to the Queen like that, and nobody would have advised her to do it that way.”

He added of Harry: “He would know that the bow, as it were, is a brief nod and the curtsy is to show respect for the sovereign, and in the case of the Queen – a lady in her 90s who actually had earned respect through a lifetime of service, and that was it.

“To do this sort of mocking thing is uncomfortable, but it is a cultural difference. It’s like you would do a curtsy if you were playing in Snow White.”

Brandreth said of the series that the trailer had been more exciting than the full programme so far.

“If you take the long view of history, you find it interesting, but you don’t find it alarming. I don’t think, for example, the King would have watched it,” he said.

“He doesn’t watch very much television. I don’t think he would have learned very much except about the unhappiness of his son in the situation. We can all learn lessons about how we run things.”