INFORMATION:

Map of Poole Harbour and Middlebere Farm. There is parking just off the road by the track entrance and beyond the farm is a hide to bird watch.
Red circle : there are many bomb craters in this area from German bombers put off by bombing decoy.
Yellow arrow to Holton Heath Cordite factory.

EXTRACT FROM ENGLISH HERITAGE'S RECORD OF SCHEDULED MONUMENTS about bombing decoys.