Arne - Mystery symbols

Whilst browsing through a previously undiscovered set of RAF HLA series aerial photos on NCAP I came across a set of white dots on a 1942 aerial of Arne, on the west side of Poole Harbour (See photos below). They are located at approx. SY 98115 88150 and also appeared, somewhat faded, in the 1947 coverage. I thought I could make out something in modern aerial photos on GE but I can't be certain. They look to be too large for a barrage balloon mooring to me but with nothing to compare at the same scale I can't be sure of that either. Any ideas.


The dots in 1942


The dots in 1947

An anti aircraft battery, perhaps ?

I don't think so there are no support buildings. I did wonder if it was for an aerial of some sort or decoy related but they don't match anything I have come across.

Thanks. I'm not familiar with LAA sites as most were not obvious from aerial photos.

The description on Pastscape for another AA battery in that area des ribes the site as

"Air photos taken in 1947 show six circular settings arranged around a circular central area within an area of open moorland"

I did suspect a target of some sort but had nothing to compare it to as FAA ORS targets . It is a possibility I suppose. Poole harbour did have a bombing target off the SE corner of Brownsea Island and the was a target marked on marine charts between the mystery circles and Brownsea Island, although they may have been for land based practice and might be related to the circles.

I will look for earlier coverage to see when they were installed.

EDIT: Had a quick look at NCAP. The latest date prior to their existence is 4 September 1940 and earliest date showing them is 21 June 1942. There didn't appear to be anything from 1941 covering that location.

Another vertical from July 1989 shows some odd features near the circle location but these may be horse jumping hurdles.