This is the third single from Scottish singer-songwriter Paolo Nutini's second album, Second Side Up.
In a review, Q magazine described this piece of swing jazz as "How Louis Armstrong might have sung had he been born in Paisley."
Having no lead in your pencil is an euphemism for impotency, so in this song the narrator is claiming to have no problems in his sex life. His "fully leaded pencil" is just one of the reasons why he's feeling so good about life.
David Bowie's "Space Oddity" tells the story of an astronaut who cuts off communication and floats into space. The BBC used it extensively in their coverage of the 1969 moon landing - an odd choice considering the lyrics.