The Peruvians knew the island as the Island of the Four Evangelists. Unfortunately, he did not know where to get hold of one. However, it is not impossible that the 500 Penrhynese also have a banner, although they live in the Northern group of islands if I remember correctly. If you like I can send you a GIF of it. I answered him, asking for the Atiu flag image and asking about any other current flags in the Cook Islands.
Proportions are exact.
There is only one flag for the Cook Islands. The Atiu emblem is the crest of Atiu.