I was flying my M2Z yesterday on Cannock Chase with my friend when I looked up fromthe controller and saw that my drone was not in the place where it should have been. So I looked around and finally saw mine way higher, I looed towards the othr one and there were now 2 more flying at about 75 feet above me.
I brought mine back over at a higher altitude and these other ones kept flying around. They disappeared for a while(i guess for a battery change) and came back again. I sent mine up to look for the guy(s) who were flying them but could not seee where they were.
I guess the motto is keep alert as I could see all around where I was and did not see anyone else.