 Complete the following phrase:  Limitations of the existing 2-pounders were apparent even as the gun entered service and an effort was made to replace it with a much more capable weapon starting as early as 1938. The Woolwich Arsenal was entrusted with the development of a new gun with a calibre of 57 mm. Guns of this calibre had been employed by the Royal Navy from the late 19th century and manufacturing equipment was available. The gun design was complete by 1940 but the carriage design took until 1941. The production was further delayed by the defeat in the Battle of France. The loss of equipment  most of the heavy equipment of the British Expeditionary Force BEF was left behind in France during 