The King is reminding train passengers on platforms across the UK to “mind the gap”.
The King and Queen Consort have recorded an announcement which is being played at every railway station across the UK and all London Underground stations between Friday and Monday, industry body the Rail Delivery Group (RDG) said.
In the message the King begins by telling passengers: “My wife and I wish you and your families a wonderful coronation weekend.”
The Queen Consort then says: “Wherever you are travelling, we hope you have a safe and pleasant journey.”
The message concludes with the King adding: “And remember, please mind the gap.”
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It was recorded at Highgrove earlier this year by the audio team from Transport for London.
RDG chief executive Jacqueline Starr said: “The coronation is a rare and exciting event and we very much look forward to welcoming passengers with this special message.
“It’s wonderful that Their Majesties are including rail passengers as part of this historic moment.”
Network Rail chief executive Andrew Haines said: “Our station colleagues are pulling out all the stops to welcome people to London for the coronation and it’s fantastic that they will also be welcomed by King Charles III and Queen Camilla.”
London’s Transport Commissioner Andy Lord said: “With less than one day to go before the coronation, we look forward to hosting Londoners and visitors from across the globe.
“We are honoured to support the celebrations with a special station announcement across our network from Their Majesties King Charles III and Queen Camilla.”