Hunslet-based Meltog Ltd started out as Melton Engineering in the 1920s in an old wooden hut on King Street in Drighlington.
The wooden hut was later replaced with a large factory on the same site, which is next to Drighlington Methodist Church.
In 1939, The English Electric Company - which made electrical industrial equipment at their factory in Thornbury, Bradford - turned to Melton to train engineering apprentices to help with the war effort.
English Electric helped the war effort in a number of projects, including the development of aircraft including Halifax bombers.
The original Melton factory on King Street at Drighlington was recently demolished to make way for housing.
During the demolition builders found a plaque dating back to the 1940s in a basement.
English Electric Company presented the plaque to Melton founder George B Melton in recognition of the factory's help training apprentices for the war effort from 1939 to 1945.
The inscription on the plaque reads: "To record the public spirited action of George B Melton who placed at the disposal of the Bradford Works this unique equipment of machine tools and apparatus which enabled 44 craftsmen apprentices to receive in this place inspired training in precision production and thereby to make a notable contribution to their time and generation."
The builders gave the plaque to the neighbouring Drighlington Methodist Church.
In the 1950s George Melton teamed up with another engineer called Mr Ogley and Melton became Meltog Ltd.
The business stayed at the factory in Drighlington until 1989.
Drighlington Methodist Church stewards David and Margaret Eastwood got in touch with Meltog and the plaque is now with them at their factory on Copley Hill Trading Estate, Whitehall Road, Hunslet.
For the past 60 years Meltog Ltd has made machinery used in the production of promotional tin boxes and general tin cans.
Meltog Ltd managing director Julian Heyworth, said: "We are absolutely delighted to receive this plaque, generously donated by the parishioners of Drighlington Methodist Church.
"It has been some 29 years since Meltog moved from the Drighlington site and this unique piece of our company’s history serves as a reminder of the altruistic principles of our company’s founder and his strong belief in training the next generation of engineers - philosophies by which we continue to be guided to this day.”
David Eastwood wrote in the Drighlington Methodist Church newsletter: "I wonder if there are still family members of the men who trained at Meltog as apprentices during the years 1939 - 1945 in our village."
He said: "The plaque is an absolute work of art. It is a real historical piece of work."
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