Are you sure you're reading the base right?
I found a miniature with "M6" written on it, until I stripped it of paint and it became "MJ7" and then used a tooth brush on it and it became "M17" and then finally, FINALLY managed to scrape away the rest of the paint (that someone had put on the base?!) and found out it was a High Captain of Aradhrynd from Mithril ("M67", in case you're wondering).
I cannot find anything with "GROCUS".