During the Second World War, some of North Mymms Park was used as a base for the American Air Force. Part of the House was used for rehabilitation of injured servicemen. After the Americans had left, some of the old nissan huts and other buildings were used as temporary accomodation for civilians who had lost their homes through bombing, whilst they awaited new homes being built in Welham Green. The area was then known as Hockey Lane. A lot of the old buildings including towers which were built for military purposes were then used for farm storage or demolished. Others remain but are redundant and are ruins. One tower actually in the Park, (which is a wooded area) it's not clear from the photos if this is one you refer to, was an estate water tower, which doubled as a dovecote. It is unused now. That can be viewed (from the outside) by the public when and if the Park is openned by its present owners. This happens at least one a year when the Red Cross are granted an 'Open Day' a tradition started by the former owners the Burns family and continued by subsequent owners.