I think it's a dummy head, probably a blowing head as opposed to an empty warhead. They were coloured red or yellow but I have been unable to establish what the clouours actually meant. The only types I have drawings for don't have the annular shroud on the tail. If it was a wartime one the air tail would not have fitted on the end, nor the earlier drogue and dashpot attachments, both for air dropping. It also looks long so this may indicate and earlier type and more likely used on ships or submarines. Not much help I'm afraid.