Critics of The Crown including Dame Judi Dench and Sir John Major must feel “rather stupid” after watching the show, its creator has said.

Before the launch of season six of the hit Netflix series about the British royal family, the screenwriter and playwright Peter Morgan said he had never worked on anything that had caused such a public furore.

“All the criticism about the The Crown’s attitude to the royals comes in anticipation of the show coming out,” Morgan told Variety. “The minute it’s out and people look at it – whether it’s Judi Dench or John Major – they instantly fall silent. And I think they probably feel rather stupid.”

Dench accused the show of “crude sensationalism” before the release of its penultimate season last year, while Major described some of the scenes as “malicious nonsense”. In response, Netflix attached a “fictional dramatisation” disclaimer on the trailer for the show.

Morgan said it was difficult to have a sensible conversation about The Crown in the UK. “Everyone in Britain, whether they acknowledge it or not, has that level of sensitivity and attachment to this family, which is why it is an absolute minefield for dramatists to explore. And yet dramatists are born to write about kings and queens. That’s what we do.”

The sixth and final instalment of the series will be released in two parts, the first one on 16 November and the second on 14 December. It will cover the deaths of Diana, Princess of Wales and Dodi Fayed in a car crash in Paris in 1997, the 2002 golden jubilee and the 2005 marriage of the then Prince Charles and Camilla Parker Bowles.

Morgan, who has twice been nominated for an Oscar in screenwriting (for The Queen and Frost/Nixon) and has won a number of Emmys, Golden Globes and Baftas, said he was confident that stopping the show almost two decades before the present day was “dignified”.

He said he had an idea about a prequel that could predate Elizabeth II, but it would “need a unique set of circumstances to come together”.

The writer said he had almost finished writing the final season when Elizabeth II died last September, and he changed the ending to acknowledge her death.

“We’d all been through the experience of the funeral. So because of how deeply everybody will have felt that, I had to try and find a way in which the final episode dealt with the character’s death, even though she hadn’t died yet.”

Morgan said he had avoided reading Prince Harry’s memoir, Spare, because he didn’t want the prince’s voice “to inhabit my thinking too much”.

He said: “I’ve got a lot of sympathy with him, a lot of sympathy. But I didn’t want to read his book.”

He also addressed media coverage of the appearance of Diana’s ghost in the forthcoming season, saying her appearance was never intended to be supernatural.

“It was her continuing to live vividly in the minds of those she has left behind. Diana was unique, and I suppose that’s what inspired me to find a unique way of representing her. She deserved special treatment narratively,” he said.

Morgan said he did not feel guilty about the “Tampongate” episode in series five, which involved an intimate conversation between Charles and Camilla, saying it was “the story of privacy being shattered … not the story of exploitation”.