By the end of 1939, the standard British army issue clasp knife was now the smaller patern, with a modified can opener
From the left, 1939 Richards, 1943 W&S Butcher, 1945 "Burma" knife by Thomas Turner, and a post war 1953 J H Thompson, which evolved into the modern NATO knife still used today. There were many variations on these standard themes, no marlin spike, no shackle, different scale materials, but these are the most common I am aware of.
The standard bexoid handled knife with marlin spike inspired many civilian copies.
From the left again, William Rodgers, Richards and a C Johnson & co with buffalo scales.
This G Ibberson (top) looks like it was made using burma side plates and springs, no WD mark so probably also civilian.
Another unusual one, this J Allen (center) has the early longer spear point blade with the later tin opener design, again no WD mark.
This is a 1940 J Clarke&Son, no marlin spike and flat scales, very little wear so may well have been issued to a desk jockey!
Finally, here is one I cannot get to the bottom of, it may not even be military, tang stamp PROPAT.18230/44 Sheffield, no makers mark. I suspect the mark to mean provisional patent, 18230, date 1944, which could make it a prototype far east Army or possibly Navy knife which was not adopted.
As usual with my posts, please feel free to correct or add anything, all wellcome, thanks for looking.