WHAT IS THIS - Cambridgeshire

I'm irritated that I cannot find a positive ID for this object.

Cambridgeshire posters, please help

wtp2.appspot.com/wheresthepath.htm?lat=5...1185&gz=17&oz=7>=1

Duck decoy was my first thought. Got one in my home village in Lincolnshire, although the layout is a little different.

What is a Duck Decoy?

It is a man made water feature. Specifically for decoying ducks to alight on, or towards, for the sole purpose of despatching an ounce and a quarter of Eley's finest shot at!

Wildfowling Richard, wildfowling!

Traditional pastime in the Fens. Dummy/model ducks are floated on the water/ponds to lure passing ducks onto landing to feed. Ducks then despatched by said Eley Kynoch or with nets fired over the ponds with rockets.

Punt guns! I am allowed to say that?

Are you all quackers? As PNK points out it is between the locations of two WW2 ranges which is why I spotted it. I dismissed it as a duck decoy because it looks too ornate but the location is right.

Kebecker, punt guns are not very sporting, Denis and I as gentlemen prefer the dawn skirmish with the Purdeys and bespoke cartridge loads (He he! mine is the military full auto with magnum loads and rate of fire 600 per minute bolted to a Motley stalk mount)

Peter I found these images on Google Earth. Perhaps they may help identify what this is.

The first image is 2007, the second is 2003, and the last is 1999.

Jack

Attached files [IMG]/community/44840=1877-Archaeological Circle near Peterborough - Mar 5, 1999.jpg[/img] [IMG]/community/44840=1876-Archaeological Circle near Peterborough - Mar 5, 2003.jpg[/img] [IMG]/community/44840=1875-Archaeological Circle near Peterborough - May 11, 2007.jpg[/img]