Prince Harry marked Remembrance Sunday at a small local service in Brackley, Northamptonshire, choosing a quiet town ceremony over the official national commemoration at the Cenotaph in London.

The Duke of Sussex was spotted among the crowds at the Brackley Town Remembrance Service, wearing his military medals and a red poppy over a dark suit. He stood with local residents for the service and afterwards went into the market to shake hands with people who had gathered.

An onlooker said Harry stayed for the whole service. "He was at the memorial service – he was stood next to the pub. He was stood there watching and then afterwards he went into the market and started shaking everyone's hand," the witness said. "He was there for the whole service – we were there for 20 or 30 minutes, and he was there before us. He just wanted to show some respect."

There was no sign of his wife, Meghan, Duchess of Sussex, at the service. Harry's appearance came despite earlier reports that he would keep a low profile for Remembrance Sunday or stay out of the spotlight altogether.

At the same time, the official National Service of Remembrance was taking place at the Cenotaph in Whitehall. King Charles led the nation in a two-minute silence at 11am before laying the first wreath, followed by the Prince of Wales. The Princess of Wales and the Queen watched from the balcony of the Foreign, Commonwealth and Development Office.

Prime Minister Andy Burnham laid a wreath alongside senior politicians including Kemi Badenoch, Sir Ed Davey, Nigel Farage, Shabana Mahmood and Sir Lindsay Hoyle. A record nine former prime ministers stood close to the Cenotaph: Sir John Major, Sir Tony Blair, Gordon Brown, Lord Cameron, Baroness May, Boris Johnson, Liz Truss, Rishi Sunak and Sir Keir Starmer.

About 10,000 veterans took part in the Royal British Legion's march-past after the service, representing more than 300 Armed Forces and civilian organisations. They included around a dozen of the last surviving Second World War veterans, the oldest of whom is 105-year-old Jeffrey Brereton, who served as a mechanic on Hurricane aircraft during the Battle of Britain.

Harry spent a decade in the armed forces before ending his military career in 2015. He founded the Invictus Games in 2014 to support wounded, injured and sick former and current service personnel. His low-key appearance in Brackley kept him away from the formal ceremony in London, where his father and brother led the national tributes.

In a message marking the day, the Prince and Princess of Wales said they were honouring "all those who have served, and continue to serve, in defence of our freedom", adding: "On Remembrance Sunday, we remember those who gave their lives in service, and reflect on the lasting impact of their sacrifice. We remember them today and always. Lest we forget."

Remembrance Sunday is held every year on the second Sunday of November to honour the British and Commonwealth military and civilian services, and all those who have died in conflict. Armistice Day falls on Wednesday 11 November, when the nation will again fall silent at 11am.