Bless 'em All is located at klik. I do not think the words were written by Irving Berlin; they sound like Rudyard Kipling. And to me they sound very much like a traditional song. And they would seem to antedate WWII, and probably WW I as well. Ewan McColl sings it on a record identified at the abv. site. And my father, who served in the American army, remembers singing those lyrics, and it appears all those others are probably just parodies. I've not heard of Bertha Wilmont, but she may have composed one of the parodies.

Lyrics to "Five minutes more" are at klak and a recording is advertised at Clique"Roll Me Over" can be located at Claque

A whole bunch of WWI British tunes are in the Cheryl Morgan songbook, for which Cluck here.