Prince Charles has disclosed his final conversation with his father, Prince Philip, the day before he died in a new documentary.

The Prince of Wales spoke to his father about plans to celebrate his 100th birthday when he called the Duke of Edinburgh on April 8.

Due to Philip's hearing failing, he had to speak up and repeated a bit more loudly: "We're talking about your birthday!

"And whether there's going to be reception!"

Philip replied: "Well, I've got to be alive for it, haven't I?"

To which Charles said: "I knew you'd say that!"

The father and son exchange comes from Prince Philip: The Royal Family Remembers, a new documentary which will be broadcast on Wednesday night.

Prince Charles, left, and his father Prince Phillip
Prince Charles recalls the last words of his father Prince Phillip

The film is set to appear on BBC One and features other senior royals as they remember the life of Philip Mountbatten who passed away aged 99 on April, 9.

The duke's other children - Edward, Anne and Andrew - will also appear to share their personal recollections of their dad, The Sun reports.

In one side-splitting story, Prince William reveals a teenager doing this Duke of Edinburgh's Award awards came face to face with the scheme's patron.

Prince Philip, Duke of Edinburgh and Prince Charles, Prince of Wales
Prince Philip told Prince Charles he would have to be alive for his 100th birthday

The Duke of Cambridge and Philip found two young walkers on the Queen's Balmoral estate who were taking part in a hike to win their award when they stopped to wind down the window and ask them how they were getting on.

William said "The smallest young chap at the back turned around and effectively said, 'Jog on Grandpa!'"

While William admits the boy's reply was actually much blunter - Philip seemed to find it hilarious.

Philip then wound the car window up before turning to William and saying: "The youth of today!"

Prince Charles
Prince Charles will appear in Prince Philip: The Royal Family Remembers on BBC1

Prince Harry appears in the documentary from California and says his grandfather was "unapologetically him" and praised his support for the Queen.

Harry said: "From my grandmother's perspective, to have someone like that on your shoulder for 73 years of marriage – it doesn't get better than that."

Princess Eugenie says she brought her son, Philip's great-grandson, August Philip, to see him before he died.

She said: "I brought little August to come and meet him. I told him that we'd named him after him.

"It was such a lovely moment. We were very lucky to do that."

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