Mary Cartwright worked at Drakelow Shadow Factory from 1943-1945 . Aged 20 , she analysed metal in its laboratory for Bristol Hercules engines . Now 91 , the great grandmother has revisited the site in Kidderminster . It was one of 26 underground factories used to produce military parts .
Mary Cartwright worked at Drakelow Underground Factory from 1943-1945 . Aged 20 , she analysed metal in its laboratory for Bristol Hercules engines . Now 91 , the great grandmother has revisited the site in Kidderminster . It was one of 26 underground factories used to produce military parts .