If the marking is JPS or JP&S, the maker is most likely Josiah Parkes & Sons, of Willenhall, Staffordshire.
If the marking is JP&S LD, the maker is most likely John Pilling & Sons Ltd, Colne, Lancashire.
The markings of the two manufacturers are sometimes difficult to distinguish.
Parkes made over 4,000,000* No.36 in WWII and Pilling over 3,000,000**.
*Actually 4,446,548 No.36M MkI between January 1940 and October 1945
**Again, 3,138,561 No.36M MkI between July 1939 and March 1945
source - WWII contract/supply papers
Tom.