I think it's likely a driver who is constantly jamming his GPS. I have seen this in work with the FAA. A driver will go past the airport or park and deliver something. We see a temporary GPS outage which have traced back to delivery drivers in several instances. I imagine their company assumes their GPS equipment is broken, but still lets them drive.
It seems like an airport would be pretty eager to identify and prevent this so it doesn't go on. Maybe the London Stock Exchange doesn't care as much, but if it messes with trades?
