 The initial idea for the album was sparked by some photographs that Anderson 's wife Jennie took of homeless people on the Thames Embankment . The appearance of one man in particular caught the interest of the couple , who together wrote the title song " Aqualung " . The first side of the LP , titled Aqualung , contains several character sketches , including the eponymous character of the title track , and the schoolgirl prostitute Cross @-@ Eyed Mary , as well as two autobiographical tracks , including " Cheap Day Return " , written by Anderson after a visit to his critically ill father . 
