This was once in the old Merstham football field. There used to be a train that ran to them to remove the quarried materials. The mine was last used in 1920 and is only 200 yes old, nothing to do with Roman. A lot of your facts are wrong. My dad used to do cave rescue and tours and knew these tunnels well and often had to rescue people who got lost down there! He has all the plans of all the tunnels and mines locally. The ‘lakes’ are just flooded tunnels. I remember going down here when I was younger, and haven’t been since as i became scared to enclosed spaces after this