'The Tudors' star plays a musician in love story 'August Rush' and is quick to point out he performed all the music himself.
Jonathan said: "I sang and played the guitar myself I recorded the songs, so I sung all my own songs on the soundtrack."
His co-star Keri Russell had to learn to play the cello for the film and was forced to practice for hours on end.
She said: "Oh boy did I have to practice. Hours and hours a day!"
The pair play young lovers ripped apart only to later discover they have a son - a musical prodigy who uses his gift as a clue to finding his birth parents. Their son is played by 15-year-old 'Charlie and the Chocolate Factory' star Freddie Highmore, who had to play the guitar, the organ and conduct an entire orchestra for the movie.