The "follow the greens" system at EGLL is not as much of a technical marvel as the system in Dubai , however the system is operated by a team of ground specialists who go through just under 300 hours of training before allowed to operate. They have a UCE scheme and yearly technical and practical checks. They are able to coordinate with multiple ATCO's and LPO's for effective, and highly efficient , flow of air traffic. The stats show that there are less incidents (pushback errors etc) when the AGLCS is operated than not. The LPO also watches the ATCO and pilots, watching and listening for errors. The system at EGLL is world class and safe. Technology can add to this by making the system safer still, but I still think you'd have to go a long way to find a better system than the one at EGLL, one that is operated by a human.