Prince Charles' popularity has taken a nosedive, a new poll has found.

A YouGov poll has discovered that just 36 per cent of people think he has been positive for the Royal Family compared to 60 per cent four years ago, while less than a fifth of people (14 per cent) would want his wife, Camilla, the Duchess of Cornwall, as queen.

Over a third of people (39 per cent) have called for Camilla to be called Princess Consort, instead of Queen Camilla, if Charles becomes king, but 30 per cent don't think she should have any rank at all.

Just over a quarter of people (27 per cent) think Charles has had a negative impact on the monarchy, up 12 per cent from 2013.

This is a contrast to Prince William, who 78 per cent of those polled said he has been positive for the Royal Family, closely followed by his brother Prince Harry, who 77 per cent voted in favour of.

Penny Junor, who has written biographies about the royal couple, was shocked by the results.

She said: "We've moved on 20 years. Charles's 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."

These results come just a week after another poll discovered almost two thirds of Brits don't want Charles to become king.

An ICM Unlimited vote for general interest publication Prospect magazine found 62 per cent would prefer either Prince William or neither of the royal pair to take over the throne when Queen Elizabeth, 91, hangs up her crown.

William, 35, attracted 46 per cent of the vote, but Charles, 68, could only muster 38 per cent.