The nod to Princess Diana in Prince Philip's funeral service

Prince Philip's funeral was family focused and without the "fuss" he was keen to avoid.

The Duke of Edinburgh also had a hand in putting together the service and picked the music himself — one of those pieces had a nod to his late daughter-in-law, Princess Diana.

'Rhosymedre' by Vaughn Williams was sung during the Duke's funeral, which was held inside St George's Chapel at Windsor Castle on Saturday afternoon (midnight Sunday AEST).

The emotional, traditional British folk song was also played at Diana's 1997 funeral.

Prince Philip had a strong bond with his daughter-in-law, the first wife of eldest son Prince Charles.

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He was known to sign off his letters to Diana writing, "with fondest love, Pa".

When troubles began to appear in the marriage between Charles and Diana, it's said to be Philip who became a self-confessed "marriage counsellor" to the couple.

In a former interview, Princess Diana's ex butler Paul Burrell credited the duke with doing "more trying to save Charles' marriage to Diana than his son".

It's understood even after the couple's 1992 separation and subsequent divorce in 1996, Diana continued to call the Duke "Pa" (and Her Majesty "Ma-Ma") until her untimely death.

It was Prince Philip who also encouraged young Princes William and Harry to walk behind their mother's cortege.

The brothers, aged just 15 and 12 at the time, were said to be hesitant to make such a public appearance amid their grief but their grandfather famously said: "If I walk, will you walk with me?"

The princes have since said it was one of the hardest things they've ever done in their life but they're glad they did it. A decision which comes down to the duke.