WW1-used Portugese Mauser-Vergueiro M1904
What makes this even more interesting is the DMGLM mark on the stock, which stands for Direçao General Militar de Lorenço Marques, the main military depot in Mozambique when it was a Portugese colony. As Portugese troops on the Western front carried British equipment, the ones used in East Africa are to my knowledge the only Vergueiros that were ever actually used in combat.
Interestingly, the German Askaris apparently prefered captured Vergueiros to anything else they had on hand. I assume because East Africans tend to be fairly small and they appreciated the lighter recoil compared to a Mauser or Lee-Enfield.