Charles faces slipping public support ahead of Diana’s anniversary
The number of people who believe the Prince of Wales has made a positive contribution to the royal family has fallen in the run-up to the 20th anniversary of Diana, Princess of Wales' death.
A YouGov poll commissioned by the Press Association found that 36% of the British public think Charles has been beneficial to the monarchy, compared to 60% in 2013.
More than a quarter - 27% - think the longest-serving heir to the throne has had a negative impact on the royals, in contrast to just 15% four years ago.
The research also showed that only 14% of the British public want the Duchess of Cornwall to become Queen when Charles is King.
Most - 39% - think she should take the title of Princess Consort instead, while almost a third of Britons - 30% - believe she should not have any title at all.
Royal commentator Penny Junor suggested the public has still not forgiven the Prince for the breakdown of his marriage to Diana, and his standing had fallen because of the publicity surrounding the anniversary.
She expressed surprise at the findings, saying: "We've moved on 20 years. Charles' reputation, I thought, was completely rehabilitated.
"He's become a much happier, more relaxed and more confident Prince of Wales and I thought much more popular as a result."
The author of the Camilla biography The Duchess: The Untold Story described Charles as "the most extraordinary Prince of Wales", adding: "I think he has been visionary over the years, the issues he's tackled have all become mainstream thinking."
But she said: "He gets a hard time because his marriage failed. He's never been forgiven for that - because Diana blamed him and he never, ever said a word.
"He's never explained what went on in his marriage. His view has always been that history will judge him. He knows that he did all he could to try and make his marriage work and he failed."
She added: "I do think it's a very difficult time for him. The question of Diana has always been a source of difficulty between him and his sons."
The Press Association-commissioned poll follows surveys by national newspapers which also found unfavourable public opinions towards Charles and Camilla.
A Sunday Express poll, conducted by Norstat, found 67% of those questioned did not support the Duchess taking the title of Queen when her husband becomes King, while an ICM poll for the Sun revealed 51% wanted the Duke of Cambridge to be the next monarch, while only 22% surveyed said Charles.
Media attention surrounding Diana has mounted ahead of the milestone anniversary on August 31.
Channel 4 has screened controversial video footage of the late Princess, who was killed in a car crash in 1997, revealing how Charles asserted his right to have a mistress.
Prince Harry, in an interview earlier this year, criticised the decision to make him walk through the streets behind his mother's coffin when he was just 12. Harry and William took part in their own television tribute to Diana with ITV, but made no mention of their father.
The YouGov survey was conducted following the furore over the Channel 4 programme featuring Diana's videos but before it was broadcast.
It shows that just 8% think Charles has made a very positive contribution to the monarchy, compared to 22% four years ago, and 28% believe he has made a fairly positive contribution, down from 38%.