The number of factory sites and personnel employed shrank considerably after the end of the Second World War .
As World War II loomed , a further 40 ROFs were built by the Ministry of Supply , from the late 1930s into the 1940s , employed around 300,000 personnel .
The number of factory sites and personnel employed shrank considerably after the end of the World War II     .
As World War II loomed , a further 40 ROFs were built by the Ministry of Supply , from the late 1930s into the 1940s , employed around 300,000 personnel .