"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."
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Passengers on the Underground, Overground, many mainline rail services and the can use bank cards instead of Oyster cards from today.
Low cloud rolling in from the North Sea tonight to give some patches of mist and fog.
Train, tube and tram passengers can use bank or credit cards to swipe open ticket barriers from today.