So what else should we be considering?
Elements are often overlooked. For example, you need to give thought to those who live in that area. Excessive numbers of people can disturb them when arriving and leaving (not to mention the toll this takes on the outdoors).
For this reason we recommend that such events should limit participants to 200 and even then these should be split into smaller groups.
Also, safety issues are very important. Make sure the event is well planned, seek advice from relevant bodies such as the National Trust, and make sure all participants and contacts are briefed and well prepared.