In a 1995 interview, McCartney recalled that the Liverpool childhood theme behind the first three songs recorded during the "Sgt. Pepper" sessions was never formalised as an album-wide concept, but he said that it served as a "device" or underlying theme throughout the project. MacDonald identifies allusions to the Beatles' upbringing throughout "Sgt. Pepper" that are "too persuasive to ignore". These include evocations of the postwar Northern music-hall tradition, references to Northern industrial towns and Liverpool schooldays, Lewis Carroll-inspired imagery (acknowledging Lennon's favourite childhood reading), the use of brass instrumentation in the style of park bandstand performances (familiar to McCartney through his visits to Sefton Park), and the album cover's flower arrangement akin to a floral clock. Norman partly agrees; he says that "In many ways, the album carried on the childhood and Liverpool theme with its circus and fairground effects, its pervading atmosphere of the traditional northern music hall that was in both its main creators' and Lennon's blood."