Songfacts®:

• This was the first song Mark Ronson and Lily Allen wrote together. After being hugely impressed by a demo he'd heard of "Smile," Ronson invited her to New York to work with him in the studio. He recalled to The Independent July 22, 2007 what happened next: "I wasn't a big name at the time, so I got all my air miles to pay for the flight, and put her up at the Holiday Inn in Chinatown. It was at the height of the Sars epidemic, and she ended up checking out and sleeping at a friend's. But she was too shy to tell me. We spent a day together and worked on a couple of things, and went to record shops where I played samples to her. Then I wrote the piano and guitar bit to 'Littlest Things,' and she sat down and scribbled for about an hour and finished the lyrics. We went into the booth to record the song. She originally wanted to do a Mike Skinner (English rapper The Streets) thing, rapping the verse and singing the chorus. But I asked her to sing it all, and she just made up the whole melody on the spot, and sang this amazing solo. At that moment I realized that this girl has a really special gift."
• In the same interview Lily Allen added that the song was "about having broken up with my boyfriend, because Seb and I had split up for a few months. We've since got back together. It must have been quite awkward for Mark because Seb was his friend, but being fresh out of a relationship I wanted to write about what was on my mind. Mark came up with the music first, then I came up with the words and we fitted it all together into a melody. That's the way I normally make songs - I write everything in the studio - and it obviously means that producers are very important to me. It's a complete joint effort."
• A young singer-songwriter called Santi White has a songwriting credit on this. She has since become better known as Santigold, whose self-titled debut album was one of the most critically acclaimed releases of 2008.
• This topped the singles charts in Argentina for two weeks.