Fire heroes have been snubbed by an overly cautious Prince Charles who is warning visitors not to come the UK in case they get stuck there, while his son William has evoked the spirit of the Blitz by keeping calm and carrying on.

The Duke and Duchess of Cambridge continued to shake hands with dozens of people and even shared a glass of Guinness on a visit to Ireland while the future king was too chicken to be in the same palace as his subjects from the colonies.

The Daily Telegraph has learned Rural Fire Service Commissioner Shane Fitzsimmons' trip to London to meet Prince Charles and represent his volunteers after the worst bushfire season on record had been cancelled at the last minute.

The fire boss was due to join a star-studded black-tie Prince's Trust Dinner at Buckingham Palace with the likes of George Clooney and Sir Tom Jones but has been told international guests should stay home.

"It is with deep regret that we need to inform you that the Prince's Trust UK has advised international guests, including staff and patrons, should not travel to London, or attend any of the events," the letter from Prince's Trust Australia chairman John Landerer said.

"No staff or Trustees from the Prince's Trust Australia will be travelling to the UK. This, of course, is very disappointing but, due to the national outbreak of the COVID - 19 (coronavirus), completely understandable.

"The main fear is that visitors may not be able to leave London. This would be most unfortunate. We feel, however, you will agree it is for the better."

A palace spokeswoman said the advice was not an order - but should be viewed as "guidance'' for international guests.

A diplomatic Mr Fitzsimmons, who had been due to fly out tomorrow, told The Daily Telegraph yesterday: "While naturally disappointed, we understand."

Even the German bombs could not keep Charles' grandparents, King George VI and the Queen Mother away from mixing with families in London's East End during the darkest days of World War II, while his mother the Queen this week carried on handing out MBEs, OBEs and knighthoods at the palace, albeit wearing gloves.

Six weeks from her 94th birthday, her age makes her particularly susceptible to the virus.

In Ireland, Prince William even joked about unwittingly "spreading" the coronavirus while meeting wellwishers.

The Duke of Cambridge asked Joe Mooney, an advance paramedic with the National Ambulance Service: "I bet everyone's like 'I've got coronavirus, I'm dying', and you're like 'no, you've just got a cough'.

"Does it seem quite dramatic about coronavirus at the moment? Is it being a little bit hyped up do you think in the media?"

Later he grimaced with mock horror as he said: "The Duke and Duchess of Cambridge are spreading coronavirus, Sorry."