Prince William and Kate ride the bus in London

Prince William, left and Kate, Duchess of Cambridge, third right, ride with television personality Barbara Windsor, second right, on a 1960's Routemaster bus as they go to meet London Poppy Day staff and volunteers in London on Nov. 7, 2013. The couple surprised hundreds of commuters, as they joined poppy sellers at a London Tube station.
AP Photo/Carl Court

Prince William and Kate, Duchess of Cambridge, surprised hundreds of commuters as they joined a charity appeal at London tube station on Tuesday -- which they arrived to by taking the bus.

The royal couple traveled on a classic 1960s Routemaster bus to the Kensington High Street station, where they met military personnel and volunteers in support of London Poppy Day.

Around 2,000 volunteers, including uniformed personnel and veterans, are hitting London's streets Thursday for the Royal British Legion's "Poppy Day" charity appeal ahead of Remembrance Sunday, when Britons honor their war dead.

William and Kate, 31, were joined by British actress Barbara Windsor, who is the RBL's Poppy Day ambassador. The "EastEnders" actress reportedly asked after the couple's son, Prince George, during the five-minute bus ride from their new home at Kensington Palace.

"He's half-asleep," Kate, wearing a red L.K. Bennett coat, replied, according to the Daily Mail. William added, "He's behaving himself this morning."

The Poppy Day appeal is aiming to raise 1 million pounds ($1.6 million) in a day.

The Royal British Legion provides care and support to current and former members of the U.K. armed forces and their families.

Prince Harry also stepped out Thursday to show support for British servicemen. He joined his grandfather, Prince Philip, in a ceremony on the grounds of Westminster Abbey to remember fallen soldiers.

Prince Harry and Prince Philip, Duke of Edinburgh, visit the Field of Remembrance at Westminster Abbey on Nov. 7, 2013, in London.