After completing his Diploma in Architecture at the University of Liverpool, Percy Johnson-Marshall was employed as Assistant Architect by Willesden Borough Council from 1936-1938, where his brother Stirrat was already employed. He worked on municipal architectural projects as part of the team under the borough engineers F Wilkinson and his successor F Wayman Brown. These included school alterations, public housing estates, a refuse disposal plant and the electricity showroom on Willesden Lane. Johnson-Marshall also worked on the design for the Willesden Cemetery superintendent's house, and it is possible that he was the main architect for this.