 Tensions soon became apparent , and while Waters and Gilmour initially worked together , playing the video game Donkey Kong in their spare time , the two eventually chose to work separately . Co @-@ engineer Andy Jackson worked with Waters on the vocals , and Guthrie worked with Gilmour on the guitars . They would occasionally meet to discuss the work that had been completed and while this method was not in itself unusual , Gilmour began to feel strained , sometimes barely maintaining his composure . Kamen too felt pressured ; Waters had never been a confident vocalist and on one occasion , after repeated studio takes , Waters noticed him writing on a notepad . Losing his temper , he demanded to know what Kamen was doing , only to find that the pianist had been writing " I Must Not Fuck Sheep " repeatedly . 
