I have a problem with identyfing backpacks on this photographs taken in 1932 in Poland. I think they may be some variation of british WW1 backpacks - some details are very similar to british packs. There is small chance that some WW1 surplus was on tests in Poland in 30's. Can anyone recognize the pattern of those packs ? Maybe not british, maybe something from Commonwealth ?

WW1 British backpacks ?