ROF Chorley was opened on 31st March 1939 by King George VI. The site covered 928 acres and has been described as the largest filling factory in the world.
There is a storage site at Heapey, around SD 60934 20318. This seems to have originally used the disused railway line between Chorlay and Blackburn but other tunnels can be seen the aerial views of the area.
The main site has been mainly built over and the storage site is still in use by a commercial company for the same purpose.
- The History of ROF Chorley by John Robert