"Kate asked what kind of music I'd been playing," Corporal Steve Johnson, an RAF recruitment officer from Newcastle, who is busking at Tube stations across London told the Press Association. "She asked me to play but then said don't because it's too busy.
"Kate was more interested in the music, while William was more concerned with the day itself and how the appeal was going. Lots of people are ecstatic to see them."
William and Kate were introduced to The Poppy Girls at Kensington Palace this morning, who have produced the appeal's official single The Call (No Need To Say Goodbye), featuring 17-year-old Charlotte Mellor, who was on crutches after a fall.
London Poppy Day organisers are aiming to raise more than £1 million today.
All funds will go towards the national Poppy Appeal fund-raising target of £37 million to allow the Royal British Legion to carry out its vital work.
The nation's biggest armed forces charity spends £1.6 million every week in direct welfare support and answers more than 170,000 calls for help.
RBL Ambassador Barbara Windsor says she's hopeful Londoners will exceed the target of £1 million.
Prince Harry and his grandfather, the Duke of Edinburgh, will pay their respects at the Field of Remembrance in Westminster Abbey.
Each will lay a Cross of Remembrance in front of two wooden crosses from the Graves of Unknown British Soldiers from the First and Second World Wars.
The Last Post will sound, marking the start of two minutes silence, after which the two royals will visit meet veterans of more recent battles.
The Duke and Duchess of Cambridge are also expected to attend separate Remembrance events later today.
The Duke and Duchess of Cambridge stunned hundreds of commuters in London today as they joined poppy sellers at a tube station.
The royal couple travelled on a Routemaster bus to High Street Kensington station where they met military personnel and volunteers supporting London Poppy Day.
William and Kate were swamped by members of the public taking pictures as they walked along the high street to the station's entrance hall.
Some 2,000 uniformed personnel, veterans and their supporters are hitting the capital's streets today for the Royal British Legion appeal ahead of Remembrance Sunday.
The Duke and Duchess of Cambridge surprised hundreds of commuters today as they joined poppy sellers at a London Tube station.
The royal couple travelled on a 1960s Routemaster bus to High Street Kensington station where they met military personnel and volunteers supporting London Poppy Day.
Barbara Windsor launched the London Poppy Appeal in Covent Garden today, before heading off on the 1960s Routemaster bus to meet William and Kate - the Duke and Duchess of Cambridge.
Some 2,000 uniformed personnel, veterans and their supporters will hit the city's streets for the eighth annual event ahead of Remembrance Day to commemorate the end of the First World War in 1918.
Fundraisers will be at 80 Tube and train stations across London's transport network and at hubs including Covent Garden, where a stage has been created for military performances throughout the day.