In the period after the D-Day landings, he was in charge of a tank repair facility in Belgium. He arrived in Germany in the summer of 1945, along with his colleague, Colonel Charles Radclyffe, when the British Army took control of the town of Wolfsburg. Russian ground troops had already located a factory in the town after crossing the Mittelland canal but were not interested in it. Then the US army found it but once again it held no interest. When the UK came across it, Hirst, sensing something was not right, quickly cleared some debris from the generating plant building and discovered it had been put there to disguise the fact that it was still operational. Hirst then found a pre-war prototype Volkswagen in a remote workshop on the site and realised that the factory could be used for producing cars for the British Army. Hence, Hirst and Radclyffe laid the foundations for Volkswagen's successful automotive business.