Looks like a standard issue British Army Poncho, not sure if they still issue them but I had one back in the 80's and early 90's. Came in Olive Drab and could be used to knock up a basha too, see the loops around the edge, we would attach bungies to them at tie to trees etc.
Here is a picture of the poncho and I just remembered it formed part of the 58 Pattern Webbing kit
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