Copthorne was joined to the M23 in the early 1980s. This involved rerouting  2 streams  that fed into Heathy Ground pond, and making an access road under the linlk. In those days the works were left open with no fencing of any kind and the public could access any part of it at weekends when they were not working. Unlike today when every single part of the new works are fenced off with security cameras reporting you to the police if you stray near them just to take a few photos.