This Alexandre Desplat soundtrack is a nice addition to an all around enjoyable film, but the real Easter Egg are the songs at the end from the movie's fictitious band, Swipe, and its leader/writer/drummer, Ben Sergeant. Mr. Sergeant's real-life alter ego is the sublime actor, Dominic Cooper. Cooper knows his way around a song or two, having sung "Lay All Your Love on Me" on screen as part of Mamma Mia! The Movie. In Tamara Drewe, Cooper has the rock star persona down cold: perma-sneer, Gemma Arterton on his arm (doesn't get better than that), yellow Porsche, drumming endlessly beneath his own portrait at his cool condo. He's even got a Flock of Seagulls starter-kit hairstyle going on.
If you've seen the movie, you know that the songs his 'band' sings are, well, surprisingly good! "This is a Low" from the soundtrack (it's the one that starts "This is a call for a domestic dispute...") is very catchy. As is the song that Cooper himself adds at the end of the movie called "Jailbait Jody." It plays through the latter-half of the credits. Definitely check it out. I enjoyed it a lot.
One of the pivotal scenes in the movie is that one where Swipe "breaks up" on-stage. I remember thinking, wow, they really got a big crowd for such a small movie. That's because the filmmakers did a little guerrilla thing putting the band on-stage at a real festival called End of the Road ('EOTR'). Reading some forums I see that not everyone caught what was going on. These folks were no doubt stunned when Cooper emerged from behind the drums to start whaling away at his bandmate! Now that's some inspired filmmaking.