I 'inherited' a Mills bomb a few years ago and can remember it around my folks' house since the early 70's. Was going to post a pic and see if it looked genuine ww2, not that I imagined there were copies around back then. Closer inspection shows a date of 10/15 stamped into the base. Not WW2! A bit of excited googling shows that aluminium plugs are unusual. The base has stamped: No5.I 10/15 DF Co. I've got as far as this being the Dudley Foundry Co but the only example I can find on the net is a brass plug. The grenade is immaculate, hence my thoughts of ww2 or post war. Will post pics tomorrow. How unusual is it, or not? Not my area!