Prince Phillip wasn't going to let a cracked rib keep him from his grandson Prince Harry's wedding after a fall in the bath a few days earlier.

The 96-year-old managed to soldier on through the immense pain for the one-hour ceremony at Windsor Castle and reception on Saturday.

The grandfather of the groom seemed cheery with a beaming smile as he arrived at the St George's Chapel with the Queen, walking unaided without a cane.

"The Duke is not a fan of showering and prefers to bathe. But he's a determined man and nothing was going to stop him attending nor would he take any kind of walking aid," a royal insider told The Sun.

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Prince Phillip took the British stiff upper lip to new heights as even a slightly cracked rib is extremely painful with a stabbing pain at each breath.

The Duke of Edinburgh was already recovering from a hip replacement operation just six weeks before the big day.

He got back in shape for Harry's wedding to Meghan Markle by walking up and down the stairs for days until he was fit enough to attend.

Family biographer Penny Junor described his attendance at the wedding, without even sporting a limp, as "completely heroic".

"Given that he is 96 years old and the operation was just six weeks ago, I think that shows what an extraordinary man he is," she said earlier this week.

"That will have meant a huge amount to Prince Harry. He is enormously fond of his grandfather."

Junor, and the millions of others watching the wedding, would not have known just how heroic the great-grandfather was that afternoon.

His surgery in April followed a series of missed public appearances, including a ceremony at Windsor Castle to formally hand over his role as Colonel of the Grenadier Guards to his son Prince Charles.

He retired from public duties last year – which Buckingham Palace stressed was not health-related – but still accompanies the Queen on some public appearances.