|Robert Pattinson plays with his guitar on set|
British builder Luke Jones witnessed the actor's generosity, and told The Sun newspaper: "We were gobsmacked when he handed the acoustic guitar to the tramp.
"Robert quickly went back to his car and drove off.
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"The busker was totally shell-shocked. He had no idea who Robert was – I think he thought the guitar was stolen.
"He was looking left and right, half expecting the police to arrest him. We asked him to play but he couldn't get his thoughts together."
A standard new acoustic guitar costs around £50.
Robert – who plays vampire Edward Cullen in the vampire series - is a keen musician himself and has recorded two tracks, 'Never Think' and 'Let Me Sign' for the soundtrack to the first 'Twilight' film.
The 24-year-old star has previously said he sees music as his "back-up plan" if his film career fails, and that he believes he will be famous when he's dead.
He said: "I am sure I'll be one of those artists that people don't pay any attention to while I'm alive, and when I am dead people will go yeah, man, that was a work of art."