http://www.facebook.com/photo.php?fbid=10150458266393026&l=c694a6764f side view
How about this
Pie cut designed helmet cover , used and slightly sun faded on the top.
The cover is bigger than the m1 US helmet ( tried to fit it ) so it's not Iraq issue, it looks without a doubt made to fit on the 1980's British headgear as seen Falklands conflict.
With the cover dropped on the floor it gives the appearance of a helmet and it looks like the mk3 turtle.