Twentysomething was released in 2003 and features some of Cullum's original material as well as some covers and standards. Geoff Gascoyne, Jamie's arranger and bass player, has worked closely with Jamie since 2001 and the piano arrangements in this book reflect not only what Jamie plays, but also the horn and string parts that Geoff has arranged for the album. Presented in an authentic jazz 'handwritten' font, this is the book to buy if you really want to know what Jamie is playing!

The book features the complete sheet music to the album, arranged for Piano Voice and Guitar; a 5-page colour section; an introduction by Geoff Gascoyne; string and horn parts and authentic chord symbols throughout.