article_snippet.sent: A wartime scientist has revisited the secret underground factory where Mary Cartwright helped build aircraft engines 70 years since the end of the Second World War.
article_snippet.sent: Mary Cartwright revisited Drakelow Underground Factory in Kidderminster, Worcestershire, where more than 700 people worked during the war (right)  to produce aircraft engines.
article_snippet.sent: It was one of 26 'shadow' sites set-up to mass produce engines and parts for military aircraft and tanks that were built underground or into hillside so that production could continue if bombed.
article_snippet.sent: With more than 700 people working at the site in Kidderminster at a time it was one of the largest underground factories during the war .
article_snippet.sent: Mary Cartwright said while the tunnels were built to protect production lines from bombing, by the time Mary Cartwright began working at Drakelow the worst of the raids had already hit the country.
article_snippet.sent: While the factory's design was so carried out to avoid raids, the worst of the bombing across Britain had already occurred by the time Mary Cartwright took up work, Mary Cartwright said. '
article_snippet.sent: But when the car manufacturer Rover Coventry factory was blitzed, bosses cited the need for a more secure setting to allow production to continue.
article_snippet.sent: Shadow Factories were then created.
article_snippet.sent: Built underground, safe from the shelling of Hitler's army, workers were free to work on engines for military aircraft and tanks.
highlights_snippet.sent: It was one of 26 underground factories used to produce military parts .