The nation's war dead were remembered during a ceremony attended by the Duke of Cambridge where the Last Post was not played by a bugler - but a steel pan orchestra.
The poignant tune - associated with Armistice Day events - is traditionally sounded by a military musician but when William visited a London cemetery to highlight its war graves, school children brought the musical piece alive.
His visit to Willesden New Cemetery in north-west London highlighted the work of Living Memory, a Commonwealth War Graves Commission (CWGC) initiative.
It aims to encourage communities to discover their local war graves and memorials and explore the stories behind the names of those who gave their lives during the First World War.
At the cemetery's Cross of Sacrifice, found wherever a graveyard has more than 40 war dead, the last post was played by the local St Michael's and All Angels Steel Orchestra.
William laid a flower with Michaela McKay, 14, just before The Last Post was played by the orchestra and a minute's silence observed.
The 14-year-old, who is a member of the orchestra, said: "William was asking me about the pans and I was telling him the notes the pans have and that it is very versatile instrument.
"He asked me if it was hard to play and I said it was 'simple but not so simple'. The Last Post is really moving and it's a privilege to play it."
William toured the cemetery looking at war graves and he also met a group of pupils from Newman Catholic College who had been learning about the stories behind the names on the military headstones.
Pupil Suell Costa, 15, told William: "Two weeks ago we came here to this cemetery and (our teacher) gave us a few papers with the names of all the soldiers buried in this cemetery and we had to walk around the graves and mark all the soldiers we found – I really enjoyed it.
"I found the sacrifice they made, they didn't even know who they were sacrificing their own lives for, incredible."
Later the Duke got his hands dirty when he had a go at planting poppies with schoolchildren at another remembrance event.
William, 34, knelt on the damp ground and dug holes with a trowel before pouring in the seeds with pupils from St Charles Roman Catholic Primary School in Kensington.
He joked: "I'm not an expert gardener, but I hope the sunshine will come out and help them to grow. I'm not optimistic!"
During his visit to Kensington Memorial Gardens, he also chatted to young footballers and pupils from Barlby Primary School, which his wife the Duchess of Cambridge visited in 2015 with her charity the Art Room.
When the youngsters told him about the school's royal connection, he joked: "Not my wife! Was she there? Obviously today is far better, I'll tell her that."
The Duke was visiting the gardens to mark its dedication to the Centenary Fields programme by the Royal Borough of Kensington & Chelsea.
William, who is President of Fields in Trust, launched the scheme in 2014.
Run in partnership with the Royal British Legion, it aims to honour the fallen of the First World War by protecting outdoor recreational space for future generations.
The Duke admired Remembrance projects the children had been working on, including poems and stories they had written after learning about the Great War in school.
Speaking to others taking a pause in their football game, he asked: "Which football teams do you support?" He reacted with mock horror as they listed Chelsea, Arsenal and even the Italian club Napoli.
Villa fan William asked: "What about Aston Villa? They're a great team. They're just struggling a bit at the moment."
Kensington Memorial Park was officially opened by Princess Louise in 1926 as a community memorial to those who served in the First World War.
Today, 90 years later, William unveiled a commemorative plaque to mark the garden's continued dedication to honouring the war dead.
In a speech before he left he said: "Two years ago I launched the Fields in Trust Centenary Fields programme in Coventry. And as we reach the midway point of the commemorative period for the Great War, Fields in Trust continues to build a living legacy to the fallen by protecting Centenary Fields in perpetuity as places for play, sport and recreation.
"At this time of year, formal acts of remembrance become a major part of our public life. This remembrance is often focused at the war memorials of village greens and town centres throughout the country, and in some cases in parks such as this - Kensington Memorial Park - opened by Princess Louise 90 years ago.
"Today, in keeping with the original intent of the park we rededicate this land as a space of public remembrance – a Centenary Field. This, and scores like it across the UK will honour the fallen of World War I by safeguarding, forever, memorial parks and gardens as public spaces to be valued and enjoyed by their local community."