Complex sentence: The group cleared the perimeter of the hall and the walled garden and a security fence was erected around the house so public access could be granted, further trees were cut down in the gardens creating an area for events.
Split into simpler sentences: The group cleared the perimeter of the hall and the walled garden. For public access to be granted, a security fence was erected around the house and further trees were cut down in the gardens to create an area for events.